Making a living in the arts has been ridiculously hard for years. Streaming killed album sales, which were already devastated by ridiculous high CD prices (label greed in action.) Self-publishing books only panned out for those who can crank out multiple books per year.
I like the idea of driect support for artists, but it is too hard. Patreon builds a wall around it's content. There is no discovery.
And who visits Bandcamp besides musicians? It is certainly not known by the general public like Spotify. Plus most people stream music now instead of buying. It is far cheaper (millions of song for $10 per month or one CD for $10.) So musicians have little incentive to make albums. Especially considering they usually have to pay for them themselves or crowdfund them. Another chore.
Substack, at least, allows the creator to send their content directly to readers via email. But it still requires creators to actively recruit subscribers.
The chore of promotion and audience-building has fallen to artists and it is exhausting. It's too much work for too little return. There is precious little time for creativity when you also have to work a day job to survive and promote your art. So artist just give up.