Regarding your "you simply don't own anything". Leaving aside the financial aspect of it, this is a purely philosophical matter. You could say that owning and streaming are means to experiences. You have more individual control over one than the other. But at the end of the day, for most people, not being able to have a say on whether they can access a given movie or song is not a big deal. Mass media is mostly a commodity. And especifically a commodity they are happy to pay someone else to manage. Sure, a pop artist might remove her music but there is thousands of other pop artists there. You can replace pop for any niche style you might fancy. If you are one of those who finds a specific media artifact not a commodity, then you have the ability to acquire and preserve a copy of that artifact. That carries its own problems of course (loss, corruption, access issues, reliability, etc).
In the age of internet, if Spotify collapses, a competitor will fill the market with pretty much the same functionality. Makes no difference to you. A company removing a song or a movie from your service means you have to search for it in the bay of the pirates instead of your favourite streaming service. Either way, you will have access to it.
When folks talk about owning your email server or having your own customised OS. Most people are not interest in the benefits that the ownership entails and are happy to pay directly or indirectly for a third party to manage it for them. The things people care about are the same as 2000 years ago. Their friends, their family, their love life, their work. The consequences of ownership of media ranks very low in the vast majority of the population.
As for the rest. The issue I see with the subscription approach is exactly what you described. People start getting used to it in other domains other than media consumption. Like cars for example, car brands introducing subs to enable your seat warmers or whatever that technically is already there, but for you to use it you have to subscribe. It's a matter of time this starts spread everywhere. And when it does there will be people who will come up with a number or reasons why it is actually fine and everybody should just go with it.
If you were a writer, then books might be different to you. Or if you were a record collector, records might be a different.
Yes, it becomes problematic when people apply that attitude everywhere but sadly it is likely where we are heading with all the consequences it will carry. Most people are addicted to convenience and will sell everything to attain it
You're repeating this benefit -- and it is an undeniable benefit -- but the other issue you're not giving any weight is that other people have other priorities that can be more important than ownership -- such as a finite amount of money to spend.
Of course, ownership is wonderful -- IF it doesn't cost more, and IF it doesn't cause more inconvenience, an IF it's even available. In other words, the concept of ownership can't be considered only in isolation.
I know all about ownership as I have over 2000 CDs that I legally purchased and ripped losslessly to FLAC files using custom scripts. Would I recommend "music ownership" like that to most others who have a casual relationship with music? No. The Spotify subscription with access to 100 million songs is much cheaper and a better financial deal for most regular listeners than buying individual CDs or individual songs at 99 cents at a time from the iTunes store.
Does my 4TB harddrive of full of *.flac files that I own let me "do whatever I want with it?!?" Well... it's not a simple "yes". E.g. My friend's music streaming subscription lets her instantly load up any of the 100 million songs to listen at the gym. On the other hand, my iPhone doesn't have access to my entire music library because it only has 256 GB of space. I guess I could somewhat duplicate the "streaming" aspect if I go through the trouble to set up some Plex media server with a vpn TailScale or Cloudflare Tunnel back to my home server. But now I get into the realm of "my music CDs owning me" instead of the other way around. I have paid over $20k in music CDs ownership to have less convenience and usability. So others paying $11.99/month for more music than my personal library with more convenience to play on any device doesn't seem so ridiculous.
But can't Spotify raise the subscription from $11.99 to $13.99 on a whim? And can't they remove Taylor Swift from their catalog without warning because of a licensing dispute?!? All true. But those negatives are outweighed by the positives of cheaper price, more music, more convenience.
Ownership is not the be-all-end-all. It's only one aspect of experiencing music.
I have conflicted feelings about all the money I spent on owning CDs and vinyl records. But then again, I didn't consider other options as I did all that ripping 20 years ago before the existence of Spotify and mobile phones.
Btw, I actually set up a server using Raspberry Pi with 1TB of storage for my music collection to be able to access it from anywhere. Funny that you mentioned exactly this case.
As for the recommendations, occasionally I listen to the bandcamp feed. Not even sure if it's based on my followings. And before that I was using one specific forum to learn about new stuff. It's not there anymore. And I don't like the idea of algorithms telling me what to listen to.
The problem of subscription world is that it fucks you over in various ways, makes you spend more and more money and attention on stuff you don't really need or need in a much lower scale than your are forced to consume. It's a much deeper and bigger problem than just the social aspect or the aspect of convenience.
And you simply don't own anything. It's like renting an apartment/house for life instead of buying one. And your rent service can be shut down at any time. I'm just not ok with this. It may be fine with young people, but the moment you start taking life seriously it becomes obvious how wrong everything is.