This is a big reason I wanted something like this. I do not currently have a server of any kind set up, but i do have a 4tb SSD that's about full with mainly Steam games on my main PC. While it's nice that I can use it as a caching server, it's less than ideal since now i can't store anything else locally, plus it makes going through my installed game library a chore, all because my buddies and I may want to play some random game we use to and I don't like having to re-download anything, So having the ability to set up a dedicated server means I can now clean that drive up for other projects I'm working on, and if my buddies say "hey, let's play X tonight", I can more easily download, play, then remove it when we're done.
