> Isn't beauty in the eyes of the beholder though?

This is a truism, and I don't even think it's that accurate. There are some universal aspects to our perception of beauty such as symmetry, balance, tension-and-release, contrast, recursion... whatever it may be. We don't need to know what it is to tell that it's there.

Maybe, but all of those are context-dependent and can operate at high levels of abstraction. The beholder needs to be able to recognize them to appreciate them. A Rothko or Pollock has those things, but that doesn’t make them automatically appreciated. Assuming you’re from a western culture, listen to some Thai classical music and see how obvious the beauty is to you.