I started painting (commercially) when I was quite young. I had an aptitude and enjoyed the process—I still have brushes that are over 40 years old.
Painting proved to be a beneficial skill in or out of the studio.
So, why not use the primary tool associated with the process itself as a support—as subject matter? I started the series in the 1980s.
And then there are all those "rules" about how to load or dip the brush and never let the paint dry on the bristles...