Time and time again, media will be removed from public viewing for nearly any reason. Online streaming services have what you want to watch only so long as their license to it is valid. Once it expires, it’s gone off that platform - and not always to another one. Or the media gets edited to remove or alter something the owners don’t want to promote.
This is even true for the varying methods of sailing. Not everything will be available indefinitely. Certainly not at zero effort. While not being as simple as signing up for a service and watching a low bitrate copy of something within thirty seconds, it’s not rocket science. You can get Jellyfin running with a small library in half an hour.
Ultimately, do what suits you. A local media server works for some. Others will have everything in a single folder and view it through VLC. It’s pretty irrelevant though when the vast majority just pay a subscription to one or multiple of the streaming companies that continue to serve watered down libraries at ever increasing prices.
I think I explained what I was talking about rather well. Trying to view a piece of media in its highest release format isn’t something that’s always feasible. Anything even a few years old can to difficult to source. Ask anyone rebuilding a library after a drive failure. It’s even worse if what you’re trying to get had low viewership - it means an even smaller pool of people bothering to host the data.
While I’m sure this is a niche situation within a niche situation, hosting your own media library locally allows offline playback. Quite nice in during a thunderstorm. Not an option with what you’ve described as your methods, but again, definitely an uncommon use case.