

There are three reasons that I can think of:
- Privacy
- Collaboration
- Accessibility / cost
Privacy. This is obvious. People don’t want their private information to be sold by corporations or scraped by AI.
Collaboration To share information with others, while maintaining point 1, people have to self host. Say, you want to archive a bunch of photos for personal viewing then you can store them anywhere you like. But if you want to share them with family, a self hosted solution is the way to go.
Accessibility / cost People want to do things for free. Many applications offer free version or demo, but features are often limited and you can’t really customize them to your own needs. In addition, applications often adopt a subscription model these days and people don’t like that.
You could ask the question for video gaming. Can a used computer do the job? Yes, but you may not be able to play cutting edge / demanding games if your computer lacks the appropriate hardware. It really depends what kind of things you want to do, for choosing hardware that’s powerful enough.
Jellyfin? You need to consider if you need transcoding. Transcode or not makes quite a difference on the hardware needs.