When MM had the chance to occur in 5% of matches, I felt complaints were warranted. After the Dev in charge listened to community feedback, and reduced the chance to 2%, this became mostly a nonissue.
When it was 5% there were many unique accounts/players making complaint threads here. Since it was changed to 2%, there is only a very small number of accounts spamming the forums with, what is, mostly a gross display of entitlement. It is very difficult to have sympathy for those who say “I hate mirror games, so I leave all MM, until the Dev removes them.”
I’ve been playing a lot of ARAM recently, and people will leave/AFK/INT in regular games simply because they didn’t like their hero choices, or a hero another player selected. When it comes to players leaving mirror games, in my experience, people usually only leave matches like all Genji/Maiev, but it’s rare for players to leave say, an all Nazeebo/Raynor game. My guess is it’s because those heroes are fairly simple, have self sustain and possess the siege potential to end the match quickly.
Perhaps the Dev will have time in the future to exclude some problematic heroes from the MM pool, they would have internal data to rely on to make an informed decision.
Either way, it’s telling that ZolZol’s constructive thread about this issue, has been mostly ignored by those complaining the loudest.
The few players still demanding MM removal, apparently, aren’t willing to compromise, or provide a solution (other than having two queues, which is probably not feasible), so in their words, they will leave MM until their demands are met.