The reason why I like forums is because it gives us the best platform to voice our opinions, good or bad. You can go into greater detail on a forum than you can on something like Discord.
Also, I really am not a fan of the moderation on things like Discord. Basically, you can be having a discussion, but if it goes on for a couple of minutes or it gets a little bit heated (by heated, I don't mean people insulting each other) a mod will come in and say "I'm shutting this down now, anymore talk of this and posts will be removed and you may be banned.
Another thing I dislike is when somebody finds out some news about the game and wants to talk about it, so they hop on Discord, start discussing it and moderators will say "we have already talked about this earlier, the discussion has moved on now, don't bring it up again".
I hate it, I think mods should be as hands off as possible. Let people speak, let people get frustrated and annoyed at things, let people vent. If it goes on for a length of time, so what. If you want to make Discord one of your main areas of communication, then you need to let players discuss things without getting a bit of a power trip and feeling like you need to step in and bring things to a halt.