This proposal is generally for sites which are behind an edge network like Cloudflare. In that case your remote IP is the IP of the provider, not your actual server.

Not always, see domain fronting: https://en.m.wikipedia.org/wiki/Domain_fronting

Or services which use subdomains for individual users, e.g. #.github.io, #.tumblr.com, #.blogspot.tld and so on.

This. Currently, the difference between accessing github.com/blattimwind and blattimwind.github.io is that, in the second case, which username you're accessing is visible to all. Encrypted SNI will also protect that part of the URL.

Not necessarily, think CDNs or Shared IPs for Webspaces.

So in reality it is just as sensitive.

It can be as sensitive. But in the best case, shared IPs provide more anonymity.