Libertarians are unable to conceptualize what 'art' even is. It doesn't bring in financial benefit, so what is it for? If it's not an advertising board with your company's logo on it, it's worthless wasted space.

Art is cool.

Painting your art on someone else's private property is not.

Pushing your political agenda in public spaces is especially not cool. I just want to walk outside and enjoy the world, don't want your political agenda pushed on me.