[whywhywhy5]

Games typically last 30-40 minutes and are heavily team-based.

This scenario makes it very easy to get agitated when a person on your team screws up badly and ends up costing your team the game.

Dota 2 has recently introduced a robust muting system that has really done a good job changing the behavior of the more... voiceful members online - this has led to an overall much more pleasant in-game chat experience.