This seems like an exceptionally bad idea. Even if if just used it for my blog, an attacker can craft a URL which renders obscene content ("Hitler did nothing wrong"), then scatter that link everywhere on the web and get it crawled. Eventually it shows up in searches, but it's definitely "on my domain." Furthermore, it's like running a public anonymous FTP, it'll just get used as a malware hosting tool as soon as it'…
In any case, I'm skeptical that you would ever use this for a blog because the links are immutable. You'd have to either change your homepage every time you updated your blog, or you'd have to dynamically render your homepage in Javascript by querying another server - and if you're gonna do that, what's the point? Just host your own stuff then.
What this gives you is a way to share static content where your entire app/page can be distributed in the url with extremely minimal server interaction. There's no risk of malware or vandalism because there's nothing actually being hosted - the URL is the data. When you share it with someone you know exactly what they're going to see when they click on it.
I can think of a lot of uses I might have for this; even just minor things like sharing quick lists with family members. Updating the URL whenever I changed something would be annoying, but the benefits might outweigh the drawbacks.
Edit: Are you talking about domain forwarding? I could see how that would be problematic. It didn't occur me because I'm not sure what the advantage would be. I don't think I've ever been in a situation where it was too cumbersome for me to host static content somewhere, but not too cumbersome for me to buy a domain and edit its config whenever I published content.