Mozilla has a user-base of like 3%.
They don't have any clout at all. They should be grovelling to and thanking any website that bothers to support them, not trying to give ultimatums.
> don't hotpatch it but send it to the vendor and tell them to merge it or else...
But this is a user-hostile approach. No thanks.
Except it is very common. Back before FF included DRM (optional) I couldn't get Netflix on Linux FF. But if I switched the UA string to FF Windows or Linux Chrome I could watch it. Contacted Netflix and they said "we don't use UA strings to block people." But it isn't just Netflix. I've seen this happen many times with many different websites (no problems since DRM is enabled on FF).
I don't disagree with you, but the amount of people doing "something wrong" is staggering. And it isn't just the little guys.
Also, Mozilla is what, 3.45%? I don't think people care unless you're Chrome or Safari (combined are ~85%).
Mozilla's response was to roll back the change instead of blaming the users. The alternative was letting Firefox lose market share to Chrome because the websites people wanted to use didn't work. At least one major e-commerce website (Flipkart) was actively losing sales because of the bug.
Mozilla trying to strongarm people into using web features the "right" way sounds like something Google would do.
When a new Chrome or Safari release breaks a website, the website is broken.
I hate myself for typing that out, but it's true. Chrome has the luxury of dictating terms to sites that IE used to have 10 years ago. Firefox has never had such a dominant position, so they need to shoulder some of the burden themselves to ensure remaining users aren't forced to switch.
And it would be a shame if Firefox didn't implement something, even so minor like a new version number, 'just' because sites break. You are Mozilla, send them a mail and give them a week to fix it, because you are f'ing Mozilla. I'm glad this is apparently just what they did here.
(Same thing when NVIDIA or Microsoft do contortions to support broken games. You already fixed the function or shader; don't hotpatch it but send it to the vendor and tell them to merge it or else...)