I think the point is that the game developers make the infrastructure around it (ie friend lists and lobbys), not itch.
But also, playing “logged in” already somewhat exists on the itch.io app. Where you can authenticate user accounts and that sort of stuff with the api, directly getting account info. Just from loading up an app. I just think This would be super useful in web projects ran on the website, bc that’s where majority of traffic comes from.
It could be like a oauth screen before loading up a game, where the user better understand what’s happening when they login, but also it’s a public website, I don’t understand the point of hiding usernames bc of privacy or anything of that sort.
Third point, about user anonymity, itch.io is a website that contains largely unmoderated (to my knowledge, I don’t really go around making virus and stuff) javascript code execution, you can already get a lot more info such as IP addresses, approximate location and that sort of stuff from users that play your games, hell google analytics tells you a lot of information about your players. I don’t understand the logic that an opt-in user identification system would be so detrimental to site security.