Why doesn't youtube shut down their public web api?

so we already know that youtube doesn't like people freeloading their bandwidth using something like invidious, piped, newpipe etc. why don't they just close the public web api and require a login or something. by requiring login they can keep track of what users are watching and if a user is watching thousands of videos daily they can rate limit that user.

are they afraid of losing their user if they do so? I personally don't think it can affect their business or profit. It will cut down their cost of bandwidth and computation costs. so why don't just cut off users that don't bring any revenue??