All ownership semantics aside, once I download a scene to my laptop, to all intents and purposes I own it.
Yes, I don’t own the rights to it so I can’t do anything with it beyond my own private use (not that I’d want to) but it’s on my laptop/hard drive and I can watch it whenever I want forevermore irrespective of whether that scene is still on SLR or whether I am even still subscribed to SLR.
The streaming option means I have to continue to pay for a membership in order to keep my access to a lower quality version of that scene and, even then, there’s no guarantee that you won’t take the scene down with no notice whatsoever as you have done many times before.
For all of those reasons, the option to download content is an attractive option.
That being said, in mainstream entertainment, downloading is not really an option. If I want to watch a show on Netflix, I have to be subscribed (or have a password for someone else’s subscription!). I can’t download Stranger Things to keep, I have to stream it and everyone accepts it. There are undoubtedly some who’d love to be able to buy a Stranger Things 4k Blu-ray box set to keep but those days are pretty much gone, not completely gone but largely gone. None of these Marvel shows, Star Wars shows, Lord Of The Rings shows etc will ever be released on dvd because they want people to sign up to their streamer to watch it and then you hopefully just don’t bother unsubscribing when it finishes. Don’t be surprised if porn goes that same route.