What's up with fps vs. fps infighting?

I just don't get it. People who play this game talk shit on people who play that game. People shit on Call of Duty the most, why does it got to get so much flak. I never understood people hating on a certain game, especially when people say that one game is inferior to another. I play CoD, I play Battlefield, I play Halo and TF2 and enjoy each equally. How do you feel about people infighting between games?

Every one shits on COD for a few reasons;
1. It's community is retarded
2. Each game has about a years worth of production value.
3. The game is too easy, has a low skill ceiling and makes casuals feel hardcore.
4. The game is completley unbalanced.
5. It provides you with the most bullshit kills and deaths.
6. NOT FUN.
I recommend CounterStrike, where atleast the '1337 pr0 circlejerk awper' has some sort of skill, and does not need COD's retarded aim assist.