I’m going on a limb here to guess you’re the sort who runs multiple accounts so “you” may have claimed that but… there’s not much evidence to actually support what you claim as “Madcat”
You have two posts regarding aram mirrors so the only one that has you saying its [implied] ‘toxic’ is your own topic requesting the removal. Only one person replied to you. “all these forum warriors telling me” 
‘Forum warriors’ is a flag you’re not really reading anything people actually post and are just feeling it out on impulse. That probably happens in other things you’re doing too 
I doubt you could find anyone that actually told someone “you’re wrong” about “aram toxicity” from mirror matches. What you could find is people saying that their experiences aren’t “Every game” – as hyperbole is the obvious norm – or that they don’t distinguish any toxicity from their regular games from mirror. I can point at that as that has been my own experiences that I’ve shared: when I get games with the same people, the ones that were problematic in my mirrors were also problematic outside of it.
Mirror aram is easy to blame and people tend to neglect actual comparisons to their other modes because they’re just looking for something to fault. Feel free to dislike it, but “rng win” is just as applicable to standard aram. Did you rng the players that aren’t trolling; did you rng a better healer/tank, did you rng duplicates of top-tier aram picks? Did you rng a hero you know how to play, or did you get murky/butcher/valeera against a team of mass sieging mages?
Some of us like actually like people that are willing to read and we want discussions, not mindless digression.
Sure there are posts regarding ‘toxicity’ but they aren’t by [you] or to [you]. If you’re going to make assumptions by bad lumping, then that’s probably also the case for your aram games too: you aren’t making distinctions to suit the complaints because that’s not the thing you’re looking to find.