Why not? People are generally always online these days and there is a lot of music out there, plenty to fill a phone many times over. Granted you might only have a few hours worth of tracks at any time but there is obviously at least one person (OP) who doesn’t.

Not to mention the way they manage their library sounds incredibly desktop oriented. This removes the need to plugin the phone.

And then like Plex/jellyfin, or audiobookshelf, sounds like this let’s you have a shared library across devices or people, even better!