I would be shocked if > 20% of Android users manage their own music library rather than using one of the standard music streaming services.
You've picked on iOS (incorrectly) for not being able to playback FLAC, then shifted argument. The point was proven that you don't need to buy into Apples ecosystem for this.
Speaking from experience because this is a continuing pain point for my music collection that includes oddball formats like flac, ogg, and others--none of which I can even get on my phone without using a cloud service.
I don't use iTunes, ever, anywhere; and I feel sorry for anyone who does.
It's not 2008 anymore.
Although before that, I made my own ringtone using GarageBand off a ripped mp3 and didn’t buy anything through the apple store.