The thing is, its a team game, but its also a strategy game. I wasn't watching the game in question (post it and I will) but the fact is, split pushing is an important part of that strategy. I understand the idea of wanting to fight the enemy team in a team game - but here is the problem. If a team is behind, there MUST be a way for them to win. Otherwise, people would refuse to continue to play. If you are severely behind in gold, and possibly levels, and look for a team fight regardless, that's not playing the game - that's being dumb.Smart play is seeking a method to overcome a superior force other than a straight up fight. ANY way in which this is accomplished is be definition frustrating.
Let me give you an example. Teemo. Teemo will almost NEVER win a fight by overpowering you. He wins by harass, picking his fights, and deliberately forcing you into a bad situation. The proper way to counter this is A) to NOT attempt to fight him him, as he will simply continue to harass, trade, and win. And B) to gain control with teamwork, and keep him weak enough to not be a threat. People who dislike Teemo so much are the ones (possibly like you, but I don't know and I don't really want to generalize or stereotype) who want to get in and just fight. No strategy, heavy thinking, etc. Teemo is literally their worst nightmare, and a massive annoyance.
Edit: ok, reading over this, I admit I come off a bit as talking down: im not trying to, and I honestly mean this in the most polite way. Just trying to give my opinion.