Except the assumption here is that improvements must necessarily be slower. But that's not necessarily true: collaboration between Chromium and WebKit was alrea

Except the assumption here is that improvements must necessarily be slower. But that's not necessarily true: collaboration between Chromium and WebKit was already incredibly problematic and was definitely slowing people down (http://infrequently.org/2013/04/probably-wrong/ http://infrequently.org/2013/04/probably-wrong/). So there's a tradeoff--you're splitting people's efforts, and that's bad, but you're also removing pain points that slow down development.