Chutten, a Mozilla data engineer, writes about Firefox telemetry, data science pitfalls and the end of Firefox support for Windows XP.
HN commenters cite his post on Firefox removing ALSA support after telemetry showed no users, which was skewed by users who disable telemetry.
A related anecdote: Firefox disabled ALSA support because their telemetry showed nobody was using it, but it turned out that the kind of people who use ALSA are also the kind of people who disable as much telemetry as possible:
https://chuttenblog.wordpress.com/2020/11/05/data-science-is-hard-alsa-in-firefox/
Disabling telemetry is like refusing to register to vote: you minimise the chance of people doing bad things to you, but you also minimise the chance of people doing good things for you. Maybe that trade-off is worth it for you, maybe it isn't, but don't complain that the trade-off exists and don't get annoyed that other people choose differently.
Reminds me of this: https://chuttenblog.wordpress.com/2020/11/05/data-science-is-hard-alsa-in-firefox/
tl;dr Telemetry indicates ALSA is no longer used. Firefox removes ALSA. Said Firefox version reaches release. Audio completely stops working for all users of some distros...that were yanking out the Telemetry.