Comment by Gormo

Cloudflare provides a very large haystack for this, but even for an nginx server with no CDN, it's still useful to prevent the hostname from being sent in the clear before the TLS connection is negotiated. This still hides the hostname from casual eavesdroppers, who now only know what IP you're connecting to, and would need need out-of-band information to map the IP back to a hostname. And they couldn't ever be 100% sure of that, because they wouldn't know for certain whether there are additional vhosts running on a given server.