If I understand right what you're getting at, I think some of that stuff comes from studying the medium and then having an appreciation for when you notice somebody is doing technically impressive stuff. The other form of it that I'm aware of, when people like read a story and get deep into analysis of its symbolism and stuff, seems like a good half bullshit at least; I say half because while they might be constructing a legitimate metaphor out of it, it's probably not what the artist had in mind and is more likely some form of projection on their part.
Ultimately, people like different things and sometimes for different reasons. And although there are consistent technical elements to a given craft (I'm not going to act like artforms are all random choice), there's also a certain amount of going by feel and a certain amount of "why did this person's work become famous but this person's didn't? dunno."
Then there are those times when we actually have an answer for why something got pushed as it did: https://www.independent.co.uk/news/world/modern-art-was-cia-weapon-1578808.html
It was recognised that Abstract Expression- ism was the kind of art that made Socialist Realism look even more stylised and more rigid and confined than it was. And that relationship was exploited in some of the exhibitions.