This is essentially moderation rule #0. it is unwritten, enforced before violation can occur, and generates zero complaints because it filters complainers out of the user pool from the start.
The no-avatars rule also takes away some of the personalization aspect. If you set your account up with your nickname, your fancy unique profile picture and your favorite quote in the signature, and someone says you're wrong, you're much more invested because you've tied some of your identity to the account.
If you've just arrived on the site, have been given a random name and someone says you're wrong, what do you care? You're not attached to that account at all, it's not "you", it's just a random account on a random website.
I thought that was an interesting point on 4chan (and probably other sites before them), that your identity was set per thread (iirc they only later introduced the ability to have permanent accounts). That removes the possibility of you becoming attached to the random name.
Why would one be concerned with being wrong at all? Being wrong, thus being able to learn, is the whole reason for having discussions with others.
Once you’re confident that you can’t be wrong, you’re not going to care about the topic anymore. There is good reason why we don’t sit around talking about how 1+1=2 all day.
This is essentially moderation rule #0. it is unwritten, enforced before violation can occur, and generates zero complaints because it filters complainers out of the user pool from the start.