I noticed on github that some developers offer to download the app from Google Play without offering other options to download the compiled file ( the compiled file is missing on github too ).
This does not only apply to applications that are in beta. Why is that?
Cost. Not financial, time. I have to release on Google Play, because everyone is there, so its the easiest place to attract users. Adding fdroid or whatever else doubles the amount of time and effort i have to spend on releasing my app. Even creating a release on github isnt free in terms of time and effort.