Anecdotally I've found a noticeable improvement since Endorsements, which this data missed.
Also the rise of Fortnite and more recently Apex Legends has led to a further decrease in toxicity that I've seen. A lot of toxic kids left for BR pastures.
That's on PC in the EU region on a high-silver current, low-gold peak SR account, casual QP-heavy play but some comp, pure flexing (as I prefer to fill rather than focus on maining one or two characters. Maining is arguably the best way to climb out to Plat).
I'm an almost ridiculously positive player with a gender neutral name and I've found being overtly positive vastly improves the experience.
It does prompt a couple of toxic responses ("kys", "fuck off" etc) but the majority is really positive. (I generally just report any toxicity.)
Playing without voice in Comp is sub-optimal, as winning is much easier with some kind of synergy. Even a basic PharMercy combo, or ultimate combos like a EMP+DVa Bomb can be highly effective.
I normally Solo Q, but playing paired with a friend in QP yesterday I had a surreal experience. One player on the enemy team insulted my friend (sexual but not specifically-gendered insult). She was playing with a non-gendered name, as Moira, and the toxic enemy player complained she was carrying us.
All the players on both teams turned on the toxic player, calling them out and highlighting why they were actually losing. I have not seen anything like it before but it was hilarious.
Stay As A Team is great in theory, but a team of 6 randomised will get rekt by a pre-made 6 stack on Discord with each other, and the matchmaker doesn't seem to take that into account.
I wonder what region author was playing on?