Earlier quoted context omitted.
A Blink monoculture destroying "the web", like the one we almost already have.
The only thing preventing a Blink monoculture is Safari, thanks to iOS platform lock-in. Firefox has negligible market share, if that was all that was left, Gecko would have to become a Blink clone to survive, nobody would code exceptions for it.
Having a single renderer but multiple browsers on top of it would vastly simplify the web for users & developers, resulting in one consistent engine to develop, test, and fuzz against.
Rather than being the irrelevance it is today, Mozilla focusing on Blink development & governance would have way more impact for billions of users, rather than some obsolete and forgotten build of Firefox.
Then all it'd take is for something like the E.U. to cripple Apple's Webkit-on-iOS monopoly for Blink to take over there too.
Having multiple renderers is just a waste of everyone's time...