No need to get wound up. It's interesting that you are equating performers with hacks, thus prompting your own emotional response. Do you understand why your brain did that?

It is true that Picasso didn't come up with the style he is known for and he merely adopted it because it was popular and would sell paintings. It is also true that he was a bit of a self promoter and tended to "forget" to give attribution of other people's works. In an AI training framing you would probably call this stealing(many have).

In any event, he pretty much industrialized his "art" from the 1950's through the 1970's. His career was more of a brand and business machine than a quest for the sublime. Many people fall prey to such marketing.

Picasso was a user of people, either for their connections, their adoration, their artistic style or what they could do for his business. I recommend reading Life with Picasso and Web of Genius both by Francoise Gilot.