Because the costs to publish online are zero there would be innumerable other copies of the work posted, meaning the initial outlay for the studio time etc cannot be recouped.

It's exactly like any other work, your plumber doesn't receive royalties whenever you use your bathroom, those costs should be paid upfront.

Yep! The costs to press vinyl and print sleeves and market the work _are_ paid upfront. So cutting off the revenue stream unexpectedly means no more expensive projects for old artists