Sorting by "last updated" doesn't really tell you anything about the app's quality, and I really do not want to install and try 30 different apps solving the same problem just to see which one is better. Plenty of people have done so before me, so just tell me which one is the most popular!
But surely there should be a way to reconcile no-spying with usage reporting through some voluntary means. For example, Debian allows users to install the popularity-contest package.
Why? You don't need to do tracking, just have a counter on the server that increases every time someone downloads the repository. What does this have to do with FOSS?
It's available here: https://dbeley.github.io/fdroid-insights/
The only "old" app I keep using is Barcode Scanner (com.google.zxing.client.android), since it's a classic that will likely never stop working.