There's also (4) - a discussion medium with an increasing number of partisan bad actors both at state and corporate level, whose interest is to gum up communication, switch the overton window or foster division by trolling.
In my opinion, an increasing problem with twitter and other discussion media is astroturfing and bot re-signalling, so I feel this needs an additional category different from (3), in that (3) is people who are incompetent. (4) would be people who are agenda-driven and/or malicious.
Or, to put it differently, (3) is about problems caused by people who can hide their incompetence. (4) would be about problems caused by people who can hide their identity.
I'm extremely pessimistic about this section of users, because in my opinion, an identity-based internet would just as radically screw up the internet in a different direction. I do feel, however, that that's the way governments are heading if things carry on the way they are.