As an example why buy games from Steam when I can get them on gog.com DRM free and make them portable (without a setup or installation step on future machines)? So, I run my own Steam Store/Library like experience on a home server using Game Vault.
I use JellyFin for video. It works for music files, but I don't really like it for audio. So, I wrote my own music app that works in the browser/phone securely across the internet from my own server.
This is so much better than paying for subscriptions..