As this is now (and has been for some time) a pattern of this kind of behavior, what's causing it? While other explanations exist, I believe it might be worthwhile to at lest consider the idea that sabotage is goal. Placing people into positions of power for so they can dismantle/sabotage has recently been a popular tactic (e.g. some of the current presidential cabinet appointments). Would anybody even recognize that this kind of tactic was happening before the damage to Firefox becomes fatal?
(to be very clear: I'm speaking hypothetically and not making any explicit or implied accusations about anybody at Mozilla)
Build a browser. Implement the standards fully. Make it scream. That's your job.