[adrr]

Twitter is a microblogging site. Not a messaging platform. He could have bought snapchat which is based on messaging.

[tomrod]

Twitter is a pool of highly capable people, a large user base, and, currently, opportunity. A messaging platform added to their microblogging service is not outside the realm. It already has DM and Vine-like video.

[adrr]

Digg tried to pivot too.

[tomrod]

Indeed. They weren't as successful after. Perhaps Twitter repeats history, or perhaps they do something new.