The same reason most people can't remember being attacked or surprised before a terrifying life-changing event. There was a comment on youtube (yeah yeah, just hear me out) that described Peterson as a bomb going off in slow motion, and Peterson being the 'flash' attempting to pull in random pieces of the shrapnel to pull it all back together. This is his method of argumentation, and it only "makes sense" because it follows a progression of the big bang and him picking and chosing from multiple sources at different speeds and distances while everyone is shocked and awed. It's overwhelming and manipulative in my opinion, no different from the various pill knowledges out there.