I think there is a relevant difference, which is that yahoo.com is basically tied to Yahoo the company in a way that gu.com isn't. You can't sell yahoo.com with

I think there is a relevant difference, which is that yahoo.com is basically tied to Yahoo the company in a way that gu.com isn't. You can't sell yahoo.com without selling a major portion of Yahoo, but the vanity URL comes more cheaply. Companies do break their own URLs, which is bad, but I think using a shortener aggravates the problem.