It goes without saying that had 9/11 not driven the worldwide Islamist terror problem into our faces, that we would probably not have attacked either Afghanistan or Iraq.* Nobody is claiming that Iraq and 9/11 are not linked in this way, or that 9/11 didn't cause a major change in our foreign policy. This type of "link" is often mentioned by the administration and others supporting the war.

This is not the same as linking Iraq to the attack on the WTC as the origin of the plot, or an actual participant, which has never been claimed by anyone in the administration, although some intelligence sources were suspicious of things like Salman Pak (no solid proof, though.)

See the difference?

*In hindsight, it was probably not bin Laden's brightest move.