That's a little unfair. But not really. Fisk's main argument is that ISIS' breathtaking barbarity has blinded journalists to one of their paramount duties: to report on "the other side of the story." As applied to ISIS, that's one of those statements that makes one recoil at first glance, makes sense when you think about it, but is repulsive anew once one sees how Fisk operationalizes it.
Journalists absolutely should examine all sides of the story, including a story like ISIS. Figuring out the "why" -- the actual undergirding ideology of ISIS and how it conceptualizes itself - is a valuable service and an important journalistic project. Graeme Woods' chilling report in The Atlantic is an excellent example of this.
But Fisk doesn't actually seem to want this. What he wants, desperately, is not the "other side" of the story but a very specific story that would contextualize ISIS into a framework of global relations he's comfortable with.
So how, today, do we tell the “other side” of the story? Of course, we can trace the seedlings and the saplings of this cult of lost souls to the decades of cruelty which local Middle Eastern despots – usually with our complete support – visited upon their people. Or the hundreds of thousands of dead Muslims for whose death we were ultimately responsible during and after our frightful – or “bloodthirsty” or “twisted” or “vile” – 2003 invasion of Iraq."Of course" we can? Maybe we can. But maybe not. There's no guarantee that ISIS' emergence is primarily attributable to Western meddling in Middle Eastern affairs. To be sure, it's doubtful that any contemporary historical phenomenon can wholly be divorced from such influences -- but at that level of generality the point becomes banal. Outside such tautological points, it may still be the case that ISIS is the direct love-child of bad acts from western governments. But it might also be the case that it is primarily the result of indigenous forces and should be related to as such.
Robert Fisk's story of the Middle East has long been one where most of the injustices, the barbarism, the death and the mutilation can firmly be laid at the feet of western (and Jewish) actors. ISIS challenges that story; it presents a different story that doesn't easily align itself with the older narrative. Ultimately, Fisk isn't calling for the "other side" to be told, he's expressing frustration that his story isn't. But sometimes even the "other side of the story" isn't the one you want to hear.