Not to mention unsearchable, poor discovery, a chat platform is not a replacement for message boards. SO is well suited to the Q&A format and Discord just isn’t.
From my experience, most questions and answers are asked and solved in forum channels, which are quite easy to search for anything you need.
On Discord? Really? My experience has been that if I don't know what the popular community discord is and what channels to search, I will simply not find an answer. For me, my Discord experience really suffers from Discord not being indexed by search engines.
Toxic? I sit mostly in tech/product servers, so I didn't spot that, but maybe you're right about places that are just "general".
You should see the discord server for the C# language. What a mess.