Earlier quoted context omitted.
Mozilla did multiple times and is doing it, sometimes even doing the work that Google is supposed to do (see e.g. the Webcompat project [1]). The point is, this problem is basically unsolvable without having the reach of Google and thus everone (incl. Microsoft!) is forced to spoof the UA. See also https://webcompat.com/
No company is "supposed" to do anything in my eyes; and I'd rather if they all did a lot less that wasn't defined as "produce this one very specific product that does one thing well". If anything, the agencies that are supposed to do anything for the infrastructure of the Internet are the various governments and the UN, to support an open Web. The problem is that at present the US, UK, Russia, China, North Korea, and…
That's probably my biggest grief with many big companies today (and probably most big companies ever), the lack of respect and decency (in general). The few big tech companies I see that show a decent amount of respect (but still a long shot from perfect) are either run by Elon Musk or Apple, with Microsoft slowly but steadily digging themselves out of their rabbit hole.