This sentiment is one of the reasons why I didn't bother in the past: it's apparently so complex that I have to learn something completely different and useless these days, before I can start learning something useful. I'd much rather just deep dive into x86_64 or ARM or something.
These days I know that older versions are still (partly?) included in x86_64 and that they're often mostly the same, but that was not clear to me when I saw tutorials for ancient architectures of which I didn't see the point.
But then, I've never taken well to the school system where you get taught something stupid first only to see practical applications later. It's why I dropped out of high school and went to do something of which I did see the use (a sysadmin 'study', because I knew I enjoyed working with computers, and that was indeed a good fit for me).
Saying that 6502 is useless is a bit harsh- I wouldn't call it an employable skill, but it's great for hobbyists who are into retrocomputing (like me).
You could deep dive into x86_64 or ARM, but in the general case you would never actually code in those (i.e., most folks trust the compiler) unless you were writing a driver or writing something with crazy performance like MenuetOS.
A little bit of Easy 6502 [0] but mostly Richard Haskell's Apple II-6502 Assembly Language Tutor [1][2] along with Virtual][ [3] . Basically I'm trying to use assorted manuals I could find in my childhood home's basement, most of which seem to be out of print (although there are some books floating around on archive.org).
