Sure, I didn't say it was the majority. But there is certainly a lot of hate for AC out there, seems like there's whole legions of people who spend a lot of effort to find any flaw in AC and then spam forum threads repeatedly harping on those issues, and some even have tabloid websites dedicated to trashing it at any opportunity. In my brief time with iRacing and rF2 it also became apparent that some people who use those sims tend to look down on anyone who plays other sims, because majorly simulation value. Not all of them, not the majority of them, but they can be a rather vocal minority. Just check around the AC forum at RaceDepartment, it won't take long to find a thread that quickly devolved into mud slinging between haters, trolls, and fanboys.
Personally, I don't get it. I think the more people in this hobby the better, regardless of what title, platform, or equipment you play on.