It was a setup between both Bret Hart and Vince McMahon, Both wCw and WWF worked on an angle that would boost the popularity of both Federations, you don't know what goes on behind the curtain and it's pretty obvious that it was a "work" Vince and Ted teamed up maybe and made "The Montreal Screwjob" which did indeed make Mr.McMahon's Character and started the Attitude Era, it also boosted WCW's fanbase as many turned on to see what exactly happened, the fans were fooled.
Ah ok, that makes sense. But then why is the incident still kayfabed, in documentaries, and books that clearly aren't kayfabed as a whole? Why are they still trying to protect the incident like it was a shoot?