I think geocities had this as well?
A lot of hosting services offer this in general. (eg render)
Tumblr? (Might not count as the control over the page is more limited. The subdomains "are" still tumblr.)
For reddits subdomains are redirects to subreddits of the same name, so I guess that doesn't count.
Also I would not consider the examples of tumblr and reddit to be relevant. A person's blog on myprofile.tumblr.org is still the tumblr organization. This would be true for reddit even if they didn't redirect. Reddit admins moderate content on all subreddits.
Or, more succinctly, when money gets involved.
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.