> But then you have absolutely no authentication whatsoever.
There are other ways. For a while, I played on a private Minecraft server which disabled authentication (for reasons; that server also had the mod which allows Bedrock players to connect to a Java server, which probably played a part). However, once you connected to that server, you had 30 seconds to type a command with a password, otherwise you'd be kicked out, and before entering that command, the player is frozen and has no access to the inventory. The closest analogue is IRC's NickServ.
That server also had a way to allow everyone to use their own user-selected player skins, even without authenticating to the skin servers, though I don't know the details on how that worked.
There are other ways. For a while, I played on a private Minecraft server which disabled authentication (for reasons; that server also had the mod which allows Bedrock players to connect to a Java server, which probably played a part). However, once you connected to that server, you had 30 seconds to type a command with a password, otherwise you'd be kicked out, and before entering that command, the player is frozen and has no access to the inventory. The closest analogue is IRC's NickServ.
That server also had a way to allow everyone to use their own user-selected player skins, even without authenticating to the skin servers, though I don't know the details on how that worked.