Most games nowadays have an option to just mute every-fucking-thing, which makes online gaming way more tolerable. That said, I still generally avoid competitive online games because of the community. Games where co-op is the central theme usually tend to weed out losers like this pretty fast, but not always.
Voice chat didn't ruin gaming until people started to consider built in voice chat a required feature in every multiplayer game. Someone like this gets kicked and banned from private ts/mumble/vent servers in a hurry.
I can't think of any times I've actually enjoying hearing some other gamer's voice. Usually I wish they'd shut up and phrase their questions in the form of a silence.
My first step in any online game is to click the options to ignore voice AND text chat. DotA games are much more tolerable without any kind of chat, which never added much to the strategy anyway.