And it too often describes a simple split in these societies, and therefore a binary choice, between different forms of sectarian authoritarianism - in Iraq it's either IS or the US and Iranian-backed government's Shia militias; in Syria it's either IS or the Russian and Iranian-backed Assad regime forces.
To take this representation seriously, we must force ourselves to ignore the very real third option – the non-sectarian struggle against the tyrannical authoritarianism of all states involved, whether Iraqi, Syrian or 'Islamic'.
Hundreds of democratic councils survive in Syria's liberated areas, alongside a free media, women's centres and a host of civil society initiatives. In Iraq too, though it holds no land, there is a potential alternative, at least a ray of hope. The Iraqi state's attempt to smother this is an immediate and regularly overlooked cause of IS's ascendance.
In his indispensable essay "The Rise of Daesh in Syria" (part of the collection "Khiyana: Daesh, the Left, and the Unmaking of the Syrian Revolution"), Sam Charles Hamad unpicks some of the more common IS related myths.
He quotes an IS statement which encapsulates the organisation's refusal to recognise any state authority other than its own: "The legality of all emirates, groups, states and organisations becomes null by the expansion of the khilafah's authority and arrival of its troops to their areas."
Why would the Sauds or Turks be so exceptionally stupid as to back an entity which aims to immediately supersede them?
Rather than funding IS, Saudi Arabia has funded its most effective enemies. The devastating rebel blitz which cleared IS out of western Syria in early 2014 was led by the Saudi-backed Syrian Martyrs Brigade.
When the Obama administration allowed, the nationalist-democrats of the Free Army's Southern Front also benefitted from Saudi largesse. So did Jaish al-Islam, an Islamist militia which has previously stooped to viciously sectarian rhetoric, but which is also the most effective enemy of IS in the Ghouta region.
IS seizes its arms from Iraqi and Syrian military bases. Most notably, it inherited vast stocks of American equipment from the fleeing Iraqi army in the summer of 2014. In addition, it is self-funding. Hamad quotes a breakdown of sources of finance from the Deir Az-Zour region, showing that 44.7 percent of revenues came from property confiscations, 27.7 percent from oil sales, 23.7 percent from taxes, and 3.9 percent from electricity charges. The sale of looted antiquities and the extortion of hostage ransoms add to the pile.
In Syria, Assad's scorched earth provided zones ripe for conquest. IS projected strength through spectacular shows of brutality and thrived on a "conspiracy of pragmatism, involving what can only be described as tacit or low-level cooperation with the Assad regime."
In Iraq, an "environment of authoritarian brutality" was the context in which the IS predecessors grew. Saddam Hussain taught brutality by example and heightened sectarian resentment in order to divide and rule. In 2003 the Iraqi state, army and police forces were dismantled not by the people but by the United States. The occupation then reconstituted Iraq's body politic according to an informal sectarian quota system.
Shia parties linked to the Iranian regime won power. For years extremist Shia and Sunni militias played out a brutal civil war on the bodies of Iraqi civilians. Eventually Sunnis aligned with the US in order to expel al-Qaeda, and Shia leader Moqtada al-Sadr dissolved his lawless Mahdi Army.
Yet the new government, then led by Nouri al-Maliki, continued to discriminate against the Sunni community. The de-Baathification pretext was used to bar even nurses and teachers from employment. Security forces routinely arrested and held Sunni men until their families paid for their freedom.
Meanwhile Maliki refused to incorporate into the army the Sunni fighters who had vanquished al-Qaeda. Facing unemployment and institutional prejudice, some drifted towards more extreme military formations, including IS.
But Iraqi morale, though wounded, was not irredeemably divided by sect. In February 2011, during the regional Arab Spring moment, a cross-sectarian and cross-regional protest movement swept the country. Sit-ins and demonstrations, sometimes with hundreds of thousands of people, occupied Baghdad's Tahrir Square, Sulaymaniyah's Azadi Square, and public spaces in Mosul and Basra.
Ali Issa's short book "Against All Odds: Voices of Popular Struggle in Iraq", a collection of statements, interviews and commentaries, is an essential tool for grasping the significance of this movement.
The protestors demonstrated against the extension of the security agreement with the United States, and against Iranian influence too. "We languish under two occupations, American and Iranian," says Uday al-Zaidi, an organiser in the Popular Movement to Save Iraq and brother of Muntazar al-Zaidi, famous for throwing his shoe at George W. Bush.
The movement also campaigned for due process, for the revocation of the informal sectarian quota system in political institutions, for transparency and accountability and for prisoner release.
This was Iraq's 'forgotten uprising'. "The near-total lack of media coverage of these struggles," Ali Issa writes, "is itself part of the dehumanising violence Iraqis face every day."
The protests re-emerged in 2012. Though the slogans were non-sectarian, and though they won rhetorical support from Moqtada al-Sadr, these demonstrations were largely confined to Sunni-majority areas. Indeed they were sparked by the government's raid on the home of Sunni defence minister Rafi al-Issawi.
Maliki steadily escalated the violence. In April 2013 security forces assaulted a protest camp in Hawija, killing 39. Sectarian battle lines were drawn. Al-Qaeda in Iraq - soon to be IS - stepped into the limelight, and the rest is war.
It could have happened differently. It still could. Iraqis actually voted against Maliki in 2010. Ayad Allawi's bloc, running on a nationalist ticket and appealing to both Sunni and Shia constituencies, won more votes, but Iran and Obama worked to keep Maliki in power.
Last month's storming of the Iraqi parliament, mainly by Shia supporters of Moqtada al-Sadr, shows once again that Iraqis are eager for change.
And Iraqi popular mobilisation has often proved itself capable of winning important victories. In 2007 it secured the rejection of the US-supported oil law. In 2010 leather workers went on strike for 53 days, gaining safety benefits. In May 2011 hundreds of workers at the South Iraq Oil Company in Basra went on strike against low wages and corruption.
Issa provides access to voices which, because they don't fit the binary, usually go unheard. Projects such as the Organisation of Women's Freedom in Iraq, which provides safe houses for victims of family violence as well as IS's rape victims, campaigns against US intervention, runs a newspaper and radio station and resists the Jaafari Personal Status Law which limits women's choice in marital matters.
"Against All Odds" indicates a potential alternative to sectarian and ethnic identity politics - one which, given the chance, could blossom. According to trades unionist Falah Alwan, "putting out a societal understanding of unity based on an objective class analysis is a serious political goal."
"The past has ruined and twisted us," says Nadia al-Baghdadi of the Save the Tigris and Marshes Campaign. "We are sick, psychologically. What we have seen has made us sick. It is not small what we have gone through." Yet she continues, even today, despite ongoing torment, there are "youth who are energised to act, who have very clear visions and specific goals."
Robin Yassin-Kassab is co-author, with Leila al-Shami, of Burning Country: Syrians in Revolution and War, and author of The Road From Damascus, a novel.
Books he has contributed to include Syria Speaks, Shifting Sands, and Beta-Life: Stories from an A-Life Future. His book reviews and commentary have appeared in the Guardian, the National, Foreign Policy, the Daily Beast and others, and he often comments on Syria on TV and radio.