There are a number of projects that do this, and some are paid.
Do they work? Yes.
Do you want to do this? Probably not.
Why not? Spotify does not have lossless / Hi-Fi audio yet and what you're getting is a lossy transcode. You would be better doing something like this with Deezer or Tidal (insert other competitors here) that offer a lossless format.
Whilst I've not done this, I would probably advise that if you are doing this that you strip the resulting file of all meta-data (everything!) and then use MusicBrainz Picard to add clean metadata back.
Same for YouTube but with Spotify you at least know what has been deleted. With YouTube such metadata is axed, too. Pathetic. A good reason for Oggify and YouTube-dl (or a fork).
The disappearing tracks is really the main problem with Spotify. I think at some point licensing to streaming services needs to be compulsory, like licensing to radio is, so that there aren't "exclusives."
I played a lot of cheap tapes back in the day. That's far worse quality than any MP3, especially if you're young and buy cheap, normal C120 tapes, and play them on a cheap device over and over.
When MP3 players were a new thing, I had one with all of 64MB flash on which I played 64 kbps music with dirt cheap earbuds. That wasn't perfect, but I still found it useful.
Today Spotify offers 320kbps, which is far superior to a lot of stuff I listened to, and my hearing certainly didn't get any better over the decades. I don't think I notice much difference above 128 kbps these days anyway.
Yeah, certainly I'll go for quality if I can have it, but less than perfect is better than nothing and I'm very far from being a crazy audiophile. Modern tech is far beyond the point where I stop caring about further improvements.
I think you are actually making the same point as the parent, given the question mark at the end of the first sentence (which I heard in a rhetorical slightly sarcastic tone)
Spotify contains a watermark as metadata. I am not sure if it can be removed cleanly but either way: the produced OGG Vorbis is of inferior quality (as is Spotify) due to watermark. If you were to redistribute the data with watermark you should use an anonymous Premium account and computer and network connection (Whonix with Tor?) which cannot be traced back to you.
Most people don't care about audio quality. Look at what they're playing music on. Shitty tinny speakers built into phones most of the time. $30 PC speakers. Earbuds. Laptop speakers. Sure, some people have actual high quality sound systems, but not enough people to matter.
Do they work? Yes.
Do you want to do this? Probably not.
Why not? Spotify does not have lossless / Hi-Fi audio yet and what you're getting is a lossy transcode. You would be better doing something like this with Deezer or Tidal (insert other competitors here) that offer a lossless format.
Whilst I've not done this, I would probably advise that if you are doing this that you strip the resulting file of all meta-data (everything!) and then use MusicBrainz Picard to add clean metadata back.