I think this is one of the few aspects where tumblr is more logical than other social networks, by using a subdomain for each user instead of the path. I think

I think this is one of the few aspects where tumblr is more logical than other social networks, by using a subdomain for each user instead of the path. I think reddit accepts this too to some extent - for example, programming.reddit.com will redirect you to reddit.com/r/programming.