Sorry, I dont agree, toxicity fixes itself, people blocks toxic players, and its enough to advertise loss of account in case of racial slur, hate speech, etc etc. One mistake, BANG lost 70 bucks, Technology deals with words and meanings easily these days, we are in snowflakes dominated times, remember?You get canceled if you dare to say what you think 
Plus today anywhere on the web there is rezdily available hard sexual content, violence, war, death and absolutely weird stuff without any age control and you think an idiot talking crap on a game chat is a problem?
D3 went on for 11 years with chat and it is and was great (out of the idiotic gold sellers that infested the chats back in the day) ,
its a great experience having a community to enjoy while in game, and D4 not really being PVP oriented will not really create toxicity and without community is gonna get boring fast and forever, just short term console fun and done.
In any case we are in 2023, social is everything, so following your logic we couldnt have discord, twitter, facebook, Instagram, forums, game chats (most have it, poe, last epoch ) etc. The few idiots trying to ruin it for others get canceled fast this days, by AI or mods, is the last of my worries. I am more worried about having paid 70+ for a game that will last a month if it will, when I played d4 For 4000 hours.
Im L67 in torment and when I am without my team, i just lose the will fast. Its depressing seeing all those lonely players silently roaming the world without being able to join them or interact. The active chat mods can be there helping AI and there will be plenty of volunteers for that if needed, included myself.
Most of the pc community is well behaved in diablo, and the idiots are just a tiny minority that can be silenced easily and these days toxic kids are mostly on consoles… Besides a bit of healthy banter is always good in life.
In my opinion they removed chat only to downgrade the whole experience to console level.And thats scary for me because means I wasted my money, but its a massive mistake that will kill diablo also, not only my expectations as a devoted fan of the franchise for 30+ years. And it wont be a player killing diablo this time, sadly…