Most people complain because they aren't good and need excuses to why they lose.
It happens in every game, I'm sure you've heard someone play a game offline and say, "man they cheating". As humans we need excuses to why we lose, and if we don't lose a certain way we find comfort in having excuses.
One Man Army+ Danger Close tubing is the only legit thing to really, truly complain about in this game. Because it's easily the G@yest thing in the game. Let's look at a few of the most common complaints...
Painkiller- sure it's lame when you get killed by some dude who's 10-30 and he ruins your killstreak by this boost, but if you're spawn trapping someone how are you playing fair yourself? I always wondered why people think spawn trapping is fair and ok???
Commando- when some guy is running around like Usain Bolt this is TRULY annoying, but it's not a deal breaker really, since after a few times, you'll be looking for this guy.
Assault Rifle low recoil- like why do some people care about this? Do you wish recoil was higher so you'd get killed less?
Camping- again what do you want? Everybody running around like Rambo out in the open? It's not that camping is okay, but most hardcore campers don't get the best scores anyway unless they are shooting noobtubes.
I see so many matches where a guy will go 50-10 or something and the other team is like "nice camping blah blah" If a guy can camp and kill you that many times(minus OMA) then you should be ashamed.
I'm not saying I'm the best, my K/D is like 1.20 but I'm just saying I've played a lot of online games, and I don't cheat or do cheap tactics. However I hate seeing people constantly complain about talk about how some older version of a game was so much better and purer.
Why was it better? Because you were actually good at it? Or was it because online play back in the day wasn't so rampant thus a lot less hacking, cheating and glitching?
Again, OMA+Danger Close tubing is LAME and worthy of complaints. Oh and boosting too. Everything else, man up and shut up