I find it difficult to understand the immaturity of not being able to separate the art and artist. It’s really not difficult. I think some of it is performative for signaling to one’s peers that they are on the “right side” of some issue or imagined virtue.

It's not about immature people being unable to separate art from artist because it's difficult. The issue is whether it's the right thing to do.

I feel pretty confident that I could describe to you a case (either real or hypothetical) where you would reject an artist based on their personal behavior, rather than their art. You would find it quite difficult in such a case to separate the two.

So the question is where to draw the line, and everyone answers that question differently.

What you are doing is not maturity, but compartmentalisation. If you simply refuse to hear a single piece of evidence of, say, Michael Jackson’s pedophilia, or Roman Polanski’s repeated rape accusations, you are choosing willful ignorance, especially since often the artist’s status and fame make their criminal behaviour possible and provides them shelter from prosecution.

I myself am far from innocent of this. For more than 20 years Polanski has been, and in many ways still is, my favourite film maker. Repulsion, Tenant, Chinatown etc. are masterpieces of cinema. But they are inherently, even on plot level (at least in the case of Chinatown) intertwined with the horror of his actions. There is no virtue signalling in my personal connection to his set of work (who would even care anyway), but for me to continue pretend I know nothing about his behaviour or that it doesn’t directly inflect upon his work would be deeply dishonest.