Hypothetical example... but what nefarious things can one do knowing that some anonymous user happens to e.g. refresh pages a lot (or even, how can that data be sold)? OTOH it does let the developers know whether removing the refresh button would affect a lot of users. Or whether moving it elsewhere is sensible (e.g. to the toolbar if used a lot, or into a deeper menu if rarely used).

Sure, this example is contrived. But in some cases features make app development more complicated (ALSA support in desktop firefox might be a better example, but I'm not super familiar with that case). Knowing that a feature isn't used makes it easy to accurately remove crufty/complicated features without negatively impacting a lot of users. And makes it possible to justify retaining complex features that happen to be useful to many users.

Same story with crash reports (typically users have to explicitly confirm sending crash reports in many applications, no idea what kind of system Focus uses though). You need to know which issues are actually important, developers don't have infinite time (as much as we wish we did).

(I used to be sceptical too... but you're sailing blind without this kind of data, and ultimately hurting both yourself and your users.)