You're kinda jumping to conclusions there Junk, only two people mentioned complaining and you didn't really give them too much to go on. That's kind of a big stretch to "all LoL players are jerks"
As for tourneys, that's part of the nature of the game. League of Legends can support 10 players per match, just like our CSS servers support 40 or so. When we hosted the Dustbowl Event in Insurgency, if 50 people showed up, someone would be left out. Events are announced far in advanced, often times we have signups...if we go overpopulation it's limited by the game.
Getting back to LoL, if it's something that's a little less formal, like a get together for some friendly matches, or tourney practice, etc. Then no problem, 15 people show up, you can break it down into 3v3 and 5v5 just by picking up 1 extra person. Or you play one 5v5 and get a second one in 30-40 minutes later.
But for a scheduled event with ranking and prizes, you have to follow the rules of the event. ECs take the time to plan and setup an event, line up prizes and you can't just toss that out the window because a few extra people didn't make the server limit.