You are making a big deal out of the chat when in my opinion it isn't.

The only instance where you might use the chat is before the match begins. Given the frenetic and heated nature of this mode, typing in the middle of a battle to tell something very specific to one of your teammates will most likely make things worse, not better. You have direct macros with a sound to give specific instructions and you have a good bunch of them.

Chatting in the middle of a match was 99% of the times used in the past to bash or harass someone, not to bring constructive feedback (which should always be saved after the match finishes, you are not going to help anybody by writing a wall of text while the enemy team is rampaging you).

I never said removing the chat was the ultimate panacea to solve toxicity btw, all I suggested is that SE probably thought that, given the situation and how insanely rude people were, the removal of the chat was the lesser evil here.