How much of audio engineering do you think is objective vs subjective?

I’m still pretty new to this so I’m curious what you all think. I’ve grown to feel that most music is subjectively beautiful and that there’s only a handful of basic principles that must be followed to make objectively good music. But that’s only from a technique and performance perspective.

Are there any essential aspects of audio engineering that you consider necessary for a good sounding mix? Are there techniques that you think are objectively better sounding than others?