Capitalism isn't when you pay for things, it's when there's capital you can sell.
These days it's both publishers and artists attempting to create RMS's world of a right to read.
Under communism artists would be barred from making art entirely, ordered by the state to work in a place where it is deemed to be productive.
It would seem that it opens you up to the problem of other people deciding whether you're an artist or not and if so whether you're a good artist.
The same of course happens with capitalism, where it's your customers doing it. (Or in the case of books, which are almost never profitable, the VC-like publishers deciding to give you advances.)
So of course the reason modern mixed economies are good is there's more than one set of people that you may be able to convince to fund you.
Sure they would, it would just be "I got paid to do this art/music piece that then someone will use in their product they sell"
Surely that's their labor? Capital is the factor of production that isn't labor (or land if Georgist.)