The purpose it was made for has become irrelevant. Everybody got smart phones, so the SMS character limit became moot, as well as the need for a lightweight interface. Everybody got Facebook, which satisfies all the text based posts people make. Everybody also got instagram, which is a much better image platform than twitter could hope to be.

The exception to all this is Twitter bots (but not MS' Tay), which are probably the most entertaining, unique, and valuable accounts that could not be mirrored on another site with the same effectiveness.