In lower-level courses, Greek letters aren't used that much (at least, I don't use them that much), so I wouldn't describe it as a fixation (or a major problem)

In lower-level courses, Greek letters aren't used that much (at least, I don't use them that much), so I wouldn't describe it as a fixation (or a major problem). Examples of use: College algebra: pi. Calc 1/2: pi, theta, capital sigma for sums. epsilon and delta to state the definition of a limit (but epsilon-delta proofs have largely disappeared from mainstream calc courses, so those two letters actually don't appear much). Linear algebra: pi, capital sigma. Some people like to use stuff like phi or psi for linear maps. I don't. On the one hand, in writing my course notes I have moved away from Greek letters somewhat in courses like abstract algebra. On the other hand, there is at least one good reason to use them: It helps you distinguish different kinds of objects by using different kinds of symbols. So, for example, I can write "f(x)" for a group map f applied to a group element x. If you follow the rule of picking letters from disparate parts of the alphabet for different kinds of things, that's okay. But I think some people prefer "phi(x)" exactly because the function phi "stands out" from the argument x. Also, if I need 4 functions "in parallel", I could use alpha-beta-gamma-delta. If I try to do this using Roman letters, I use f, g, h, ... now what? ("i" is sort of reserved for indexing; "e" might mean the constant, but in any case is not often used to name a function.) You can subscript (f_1, f_2, f_3, f_4) but that introduces another kind of notational density and possibility of confusion. There are tradeoffs both ways. There are places where I'm definitely in sympathy with the your general point. I've sometimes read something and wondered why the writer didn't just use a Roman letter (particularly when I don't recognize the Greek letter - is that a capital Greek whatsis or an emoji?). Sometimes, people use calligraphic script caps (e.g. for ideals), not realizing that they will be a pain for handwriting or TeXing notes. And in some subfields of math, people seem to like Fraktur or Hebrew characters which are a real nuisance (it took me a few tries to learn how to handwrite a passable aleph), particuarly when they're handwritten and the person writing has shitty penmanship so you can't tell what letter they wrote. I agree with the general point, though: Greek letters should be used like seasoning.