I guess if enough people use it, doesn’t the tag become kind of redundant?

Almost like writing “Code was created with the help of IntelliSense”.

I don't think so. The tag doesn't just say "this was written by an LLM". It says which LLM - which model - authored it. As LLMs get more mature, I expect this information will have all sorts of uses.

It'll also become more important to know what code was actually written by humans.