Why require user account, if you don't allow new users to do anything?

Too often an interesting Google search result is a TikTok video and TikTok won't allow watching video on mobile without account.

So I finally gave up, I made an account.

But why won't they allow me to use it properly?

Yes, I can now watch videos from Google results. But if I find interesting channel and try to follow it, TikTok only pretends that I can do so. But it won't actually save into my account!

Same with favourites. What is the point?