No, I don't think self hosting is the solution. I still remember the times when every label had its own little online shop for mp3s. Those were dark times: not only did you have to register at every shop separately, most of those shops where just plain unusable: no pre-listening, broken id3 tags, downloading each song from an album separately, charging extra for higher quality, no accompanying artwork, etc. As I've already written: I think Bandcamp does it very well, and IMHO it is currently the best shop for indie musicians to sell their music online.

If you're promoting music which is deemed to be copyright infringing you will have the same legal problems as if you were hosting it yourself.

Sounds like this is something Gumroad could do if they added a marketplace to list the items for sale on their platform. Difficult to categorize all those items but worth it. I'd browse.

I emailed them ages ago about being able to browse, but them and vhx.tv are not really into doing that now. Maybe later but for whatever reason they want people to reach their site and buy through the content creator's reach instead of having a searchable archive.

Building out that promotion network is the hard part.

A thousand times YES!!!