They also tended to say the changes made it 'hard to follow' or 'ruined the pacing' or other things, but as an anime-only that just flat wasn't true. I actually really loved the kind of elliptical feel of the story in S1.
I honestly kind of felt that source readers were border-line brigading posts about the anime on reddit. It certainly didn't make me any more inclined to check it out!
One kind of interesting twist on that is Fincher's The Game. It remains unclear until the very end of the movie whether the main character is in a convoluted game where people are pretending to conspire against him, or an actual conspiracy using the game as cover.