You could probably add blood to that list too. I’m not sure it even applies seeing as sometimes it is not even possible to buy/sell blood and I should clarify that I only heard about this on a tech related stand up comedy. It made for a good joke nonetheless.
take a look at plex or jellyfin for example. these are media servers that can be setup to automatically organize your media library and keep track of what you have downloaded, what series you are watching, what episodes you have watched, etc. also like you mentioned they also provide some sort of streaming service where you can watch your media over the network without having to download it on every single device.
I’d also like to mention that usually downloading is done using an external software like sonarr or radarr that fall in a gray zone in terms of legality so be careful if you ever plan to go that route.