They're playing way too much, they're getting fed up with frustration and will eventually express it through flaming, it becomes a habit and they start label everything they don't like as trolling, inting and whatnot.
The matchmaking system is far from decent, however the community is not helping either! When they get autofilled, they have the choice to dodge and lose -3 LP instead of triple the amount. They choose not to, and ultimately they will either get flamed because they ABSOLUTELY SUCK or they will FLAME THEMSELVES.
_**Fact : In SEA, you're limited to a couple of (1-3) hours of gameplay, guess it's for your own sake.**_