Good observation. Yes, usually you aren't allowed to let anyone else use your account. However, there are some exceptions to this if you message chess.com support first and get permission; I'm pretty sure GothamChess (Levy Rozman) took the time to set things up professionally.
Mostly allowed for some content (like his channel) or also accounts made for a specific purpose like playing Hand and Brain Chess.
You just need permission from chess.com first.
Although I’m a bit late to this, but there are videos of Levy Rozman’s wife using Levy’s account and in the Fair Play Policy of chess.com, there are rules stating. Do not allow anyone else to use your account and do not use anyone else's account.