Yes, I went to a few of those protests. Despite the popularity of opposition, there were still plenty of people arguing in support of attacking Iraq. In fact I'd say that most people were in support of it. "They hate us for our freedom", "fight them over there instead of here", and general reflexive arguments supplicating to power. That's the dynamic I'm talking about.

Whether invading Iraq would have still happened without that popular support is besides the point. The point is there was full-throated support from many people, who would reflexively reject dissent while parroting corpo media talking points, and who then only came to see what a poor idea it had been over time.