> Now, that a small group of people with very specific opinions and preferences is the same that disproportionally also opt out of sending telemetry... I don't see how that is Mozilla's problem.
I disagree. If you create a piece of software and develop a userbase that disproportionately opts out of telemetry relative to your software's alternatives, congratulations, you won. You got the power users, the developers, the people who care enough to submit quality bug reports, they're all on your side. Game over.
You don't need telemetry to understand what features these users need because they will tell you - loudly and forcefully - in bug reports filed if you break something. Assuming we're talking about open source software, and we are, they may also be the people sending you patches and improvements for these features.
Telemetry is what you need if you're making a mass market product that meets the needs of 80% of users. It isn't necessary, and in fact may not be useful, if you're developing software designed around the needs of the people contributing to the software. Some software tries to do both. But the way you do that isn't by looking exclusively at telemetry and then pretending that what you see there describes the behavior of all user categories, at least when it comports with the plans of your UX team. It's by listening to the people who are most passionate about the software.