It's been done, starting from plotter based solutions years ago, through the work of folks like Thomas Lindemeier:
https://scholar.google.com/citations?user=5PpKJ7QAAAAJ&hl=en...
Up to and including actual painting robot arms that dip brushes in paint and apply strokes to canvas today:
https://www.theguardian.com/technology/2022/apr/04/mind-blow...
The painting technique isn't all that great yet for any of these artbots working in a physical medium, but that's largely a general lack of dexterity in manual tool use rather than an art specific challenge. I suspect that RL environments that physically model the application of paint with a brush would help advance the SOTA. It might be cheaper to model other mediums like pencil, charcoal, or even airbrushing first, before tackling more complex and dimensional mediums like oil paint or watercolor.