To expand upon your comment.... those startups used something.ly domains when they were small and just starting out -- i.e. before they could afford to buy some

To expand upon your comment.... those startups used something.ly domains when they were small and just starting out -- i.e. before they could afford to buy something-ly.com. Once they had traction and raised money, they purchased the proper domain. It's the same reason TheFacebook later dropped "The".