Servo, while a research project, is also a place to build the fastest possible implementation of a browser (w/o full backwards compatibility), then crib the best performing parts and move that into mainline Firefox (what Project Quantum is, a metered replacement of Gecko).
Swapping out the jet engine of Firefox in flight (Gecko) was likely to be a very bumpy, messy road, thus Mozilla has chosen to break the problem down into manageable chunks by having a parallel team build Servo and push the bleeding edge of performance & features, while having another team break the new code (Servo) and the old code (Gecko) apart into the separate , interchangeable pieces, then clean up standards compliance in the new Servo module and prep it to be replaced.
Essentially, its the Cathedral vs the Bazaar all over again. Microsoft Edge was a ground up rewrite of most of the browser (the Cathedral model of software dev) along with Android (built behind closed doors at Google, then code dumped right before a new major release). Mozilla didn't like how this model could easily backfire, choosing a more metered approach by developing smaller, swappable components in the open.
Swapping out the jet engine of Firefox in flight (Gecko) was likely to be a very bumpy, messy road, thus Mozilla has chosen to break the problem down into manageable chunks by having a parallel team build Servo and push the bleeding edge of performance & features, while having another team break the new code (Servo) and the old code (Gecko) apart into the separate , interchangeable pieces, then clean up standards compliance in the new Servo module and prep it to be replaced.
Essentially, its the Cathedral vs the Bazaar all over again. Microsoft Edge was a ground up rewrite of most of the browser (the Cathedral model of software dev) along with Android (built behind closed doors at Google, then code dumped right before a new major release). Mozilla didn't like how this model could easily backfire, choosing a more metered approach by developing smaller, swappable components in the open.
https://wiki.mozilla.org/Quantum