> MPD works great for non-tech-savvy friends over, you just need to install a web-based client and they can point their smartphone browser to it.

There are different standards for this: my non-technical friends could probably browse to a local website on their smartphones. My parents would forget how to do it each time, and would be annoyed that it doesn't look like Spotify or Apple Music.

As it is, everybody on my network is able to auto-discover the Pi using their phone or computer's native AirPlay/DLNA support and play music using their application of choice (meaning my server, their own MPD server, Spotify, whatever). That kind of flexibility was a necessity for my case.