I see, that's a valid way to think of domain ownership.

When I read > I have been taught and tell my users to check the domain to verify a website is real.

I was thinking more of control of the content as "ownership" of the domain.

The point on hosting providers is well taken. You do have to consider x.pages.dev as the wild west not cloudflare of course. One difference though is you will never receive an email from x.pages.dev asking you to do something. The domain ownership still does play a part.