That's the same disadvantage with a URL. If you just wrote "whatever.com" the main problem is that you probably don't want to go to whatever.com, but some child page. But the main reason the child page isn't it's own site (like "whatever-child.com") is because you'd have to buy a new domain or go through some registration mechanism to make it act like that.

But if you're willing to pay and register, why wouldn't you just write the URL of the site you paid for and registered? Not only is it writable, but it's human readable and type-able, too...

So the big advantage is that it's probably cheaper, (and maybe splashy and fun.) And unless these get popular, nobody is going to know what it is, so you have to write "Go to www.meshtag.com and download meshtag so that you can see our message!" Which is a bit like hiding your product in someone else's store.

(But that's probably why I'm an unimaginative cynical clod.)