The Arab Spring was a big disappointment to al Qaeda, which saw itself as the most qualified to liberate the Moslem world from all its problems. Worse, many of the Arab Spring leaders were calling for democracy. Al Qaeda considers democracy un-Islamic and just another bad influence from the West. But al Qaeda also noticed that Islamic political parties did well in elections that followed the overthrow of several Arab despots. But these Islamic parties were wary of al Qaeda, even though al Qaeda had blamed the terrorist slaughter in Iraq on others. This did not deceive anyone. As a result, in the last few years, al Qaeda has tried real hard to reduce the civilian body count, and concentrate on killing soldiers, police and politicians instead. So as al Qaeda showed up in the new Arab democracies, they were warned that any rough stuff would be met with rougher stuff.
And killing Osama bin Laden made it obvious that their jihadi saviors are mortal. Not mentioned is that al Qaeda has had their butts kicked on two major battlefields (Afghanistan and Iraq). Winning would have made the carnage less offensive, I'd bet.
It will be a while before passions cool over the Iraq War and we can assess whether the Arab Spring was inspired by the liberation of Iraq. Although in early 2005, before Iraq exploded in sectarian violence (by mid-2006) when Lebanon was experiencing a Cedar Revolution and democratic reforms percolated in the Arab world, the idea wasn't so controversial.
But I think we can thank the Iraq War for the narrow opportunities that jihadis have to exploit the fall of despots in the Arab world. The despots were going to fall eventually. And one reason the realist camp has for supporting those despots is that something worse--jihadi regimes--will take their place. Without the Iraq War where al Qaeda and jihadis in general wrecked their image, those eventual revolutions--even if the liberation of Iraq did not hasten that day--would have put pro-jihad Islamists in a good position to exploit the chaos and take charge.
And as I've said all along of democracy in Arab countries, if we focus on the process that excludes the violence-prone and not the outcome, free elections that happen more than just once to choose the new dictator will provide voters the chance to decide whether putting Islamists in charge was really a good idea. Give them many opportunities to elect good men and they'll eventually do it. Even if we can't exclude the violence-prone from participating in their elections, their bad image earned in the Iraq War may be doing that job for us.
Call it blowback for the jihadis, if you will.