This is a mistake we see happening over and over. Most prominently with Facebook right now. Social networks should just stay in their lane, it's fine to steal

This is a mistake we see happening over and over. Most prominently with Facebook right now. Social networks should just stay in their lane, it's fine to steal (copy) features and ideas but changing your whole network to copy another site just because they're 'flavor de jour' is stupid. Twitter and Tumblr are two fundamentally different sites, trying to change one to the other will just destroy it. Tumblr already destroyed themselves when they banned porn and Twitter has a large porn base.