Years ago I had several huge music video playlists which today stand at 80% of what they previously were.
For anyone stuck in this situation and willing to spend a few (many) hours to recover the titles of their YouTube playlist: On the playlist page, in the (...) menu there is a "Show unavailable videos" button. After clicking that, you can right-click all the unavailable videos and copy their URLs. Then you can either try the wayback machine, or google the video ID. Usually you will find some forum posts talking about the video and mentioning the title.
Of course, it's not guaranteed that you'll find anything this way. But I have recovered multiple playlists this way.
But yeah that ease to find new things is one positive aspect of Spotify. Also to have it everywhere available. So maybe going both ways would be the solution. Using Spotify while buying/ripping/whatever the music that I really deeply value
There is an effort that it takes to get on the airwaves that is not there if just anyone can play music online. The effort acts as a quality filter on the person's taste and passion.
Beyond that, I always check out what Pitchfork thinks is good new music.
The youtube algorithm has also recommended me some of my favorite, more obscure artists but that happens like once every 2-3 years.
I have seen so many songs disappear from Spotify lately that I am considering to hoard music again. Gladly I have most of those that disappeared on my HDD anyways, since it's been mostly old songs, but yeah. Was kinda frustrating. Maybe it's the task for this winter to go through my spotify playlists and find out which music I do not own yet