TL;DR voice comms would be better than none, even with trolls.
It would be so much better to have voice comms that you can mute to have no voice at all.
In Overwatch, 99% of the games have voice comms specifically for people to call out "Bastion/Turret in the right room" or "Sniper is on X ledge". There have been exactly 3 people that I have considered muting, and ALL THREE were people who simply didn't have their push to talk enabled, after which I said in voice "Hey X can you enable push to talk" to which all 3 have responded "Oh my bad" and seconds later it was silent.
Please, Riot, I know that for some reason your team has decided prematurely that voice comms (And replay?) would be "toxic", but you really need to get over your personal viewpoints and realize that it would help IMMENSELY more than it would hinder.
I know that the instant that people heard screaming, loud music, or other annoying static in headphones, they would mute that player.
It would honestly weed out the toxic players better than the current report system does.
Of course, all of the people who work for Riot will ignore this, and we'll continue to have a shitty game that (literally, based on your own activity numbers) thousands of people are quitting by they week.