> artists have already incurred the costs to produce the content, their costs do exist.
no one is arguing that their costs don't exist, but that they have nothing to lose to put it on. It's not like the artist will somehow have a lower cost by _not_ putting it up.
Except they do have something to lose if they put it on. They will have a lower profit if listeners that would subscribe to another paying service or buy their music switch to Apple streaming.
> They will have a lower profit
You have zero evidence of this. We don't know and may not know for a number of years whether Apple Music is more profitable for artists (or not) than competitor services.
Apple built a service that wouldn't exist without the content. The content would still exist on other services without Apple though.