I’ve seen this sort of reactionary response in mathematics and music as well.

When talking to a musical educator complaining about struggling students just starting out I’ll say “I found it extremely helpful to paint the C major scale on my guitar when learning music theory.”

And they respond “Well what about chromatic 12 pitch atonal music?! What would Anton Webern say?!”

As someone who has studied GR (at the grad school level) and music, no, that's a terrible analogy.

In GR terms, Levi-Civita is more like "This is a major scale and you need to know it" than serialism.

Some subjects are just plain hard and only accessible to smart persistent people.

GR and QFT definitely qualify - but they seem to be warm up exercises compared to whatever Quantum Gravity will eventually become.

Eh, no. The problem with your analogy is that the “not linear algebra” bits aren’t esoteric, rarely practiced or used edge cases: they’re the core of the mathematical model.