You mean "on their own subdomain", right? Subdomains are domains and tumblr.com is a subdomain of com. And com is a subdomain of " " for that matter. RFC 1034.

You mean "on their own subdomain", right? Subdomains are domains and tumblr.com is a subdomain of com. And com is a subdomain of " " for that matter. RFC 1034. So why misleading?