It sure helps. That's the whole point. And it does determine what areas of music somebody can get into, and the way they do it.
Suppose I want to teach somebody about flams. I can give them this page of stuff, and we can get to work showing them how it's played, then they can go home and practice it in a focused way, by playing through it a bunch times, doing extra work on any parts that are hard for them. We got a plain and direct telegram from Mitchell Peters on what to practice to get your flams together, and we're lucky to have it.
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For a non-reader, learning the piece is out. They would be dependent on someone to teach it to them, while avoiding showing them how to read it in the process*-- which would be prohibitively wasteful of everyone's time. Maybe somebody made a video they can copy it from, but then they're still dependent on someone else's ability to read. The only position with any integrity is to say
that's not worth doing, and not learn about flams. Or learn about them some other way they devise themselves, based on no knowledge of flams.
Part of musicianship is learning materials and knowing literature, so this is an example of not being able to read determining someone's level of musicianship. Maybe this one snare drum piece isn't such a big deal, but not reading is a blanket dismissal of all of it. Basically:
Everything written = no value to me.
That's a lot for a person serious about music to give up.