What's wrong with the feedback they get through traditional channels, though? There's already a GitHub issues page and the forums. There's no need to exfiltrate user data to figure out something they're already telling you.
I also used Firefox Nightly for a while because of the massive performance improvements at that time. As Audacity claims they're doing it for UX improvements, it would be easy to get frequent Audacity users interested in a beta build featuring tracking but also all the improvements being tested.
[0] https://www.networkworld.com/article/3185461/windows-insider...
In an audio program one often uses a set of filter by default, which aren't that important.
Important is the filter I use once in a while and in that specific situation is making a huge difference.
Unqualified usage counters lead t wrong conclusions.
Someone I know well created one such, based on a common reporting template of a major Free Software project, after realising that the template itself was based on information readily obtained from the system. Fleshing that out a bit resulted in an automatic syste self-documentation tool. They'd introduced it to the support group at one former company, and informal feedback several years later was that this was the principle diagnostic utility for the team. There was no ongoing telemetry, merely a "here's the script, run it and send us the output". (If necessary, the output could have been automatically emailed or transmitted by other means.)
There are now several of these, the "About This Mac" utility on OSX, as well as several for Linux, of which I'm aware.
No, they're not app-specific diagnostics, but precisely the same principles apply.