I use Discord regularly but only one channel that is made up of people I've known for 10+ years. And they are all people I knew from a message board. The way we use it is functionally a group chat with different threads. It sits kind of between a message board and a group text. So, it's not what I assume Twitter is like.
It is also good for streaming content because, I think, it was made as a platform to watch game streamers. So, you can use it for voice chat, video chat like Zoom, or text based. It could work for HDTGM Classics except I've only streamed stuff and used voice chat; I'm sure a text chat can be done if kast ever stops working.
I'm not sure I'd join an HDTGM discord because it could be thousands of people and, at that point, it may as well just be Twitter without character limits (except the mods on Discord can just boot problem people I believe).