You're right, but I mention those two because I believe Warhol was the most famous early adopter, and Hirst is the most notorious, being the richest artist in the world.

Early adopter of something that dates back to at least the Middle Ages? Earlier, really, if you consider that a lot of Roman statuary was mass-produced. And I'm probably missing out on non-Western-culture examples.

I may be wrong but my understanding was that the Renaissance painters would use their assistants/apprentices to perform all the more tedious and time consuming tasks, which in those days including making the paint itself. And in terms of the actual painting, several stages of underpainting and the less "interesting" passages of the painting (e.g. backgrounds, clothing) would be done by assistants, leaving the artist to work on the focal points of the painting (e.g. faces).

This is very different to getting assistants to create "original" dot paintings, working to a formula, where the artist's hand only intervenes to sign the work.

And I'm not saying it wrong, or not art, just that it is fundamentally different to the old tradition of studio assistants.