One of the things you learn after writing code long enough, is that there is no such thing as a perfect abstraction, or even a non-leaky one. Eventually you run into edge cases, either in performance or functionality, that causes you to add warts to your abstraction.

Stipulating that no abstractions are perfect shouldn't be an excuse to abandon the entire notion. There's still a gradient of more or less elegant and flexible abstractions.

This definition of art, though not wrong, is so expansive as to be meaningless, especially in the context of this discussion.