This is not to say the ability to read music somehow hurts your musical abilities. Sometimes thing are simply not that correlated. E.g. having an absolute pitch - does it help to become a great musician/composer? No one knows.
From that page: "do you even really need to read music to become a good jazz musician? It seems like everyone tells you to NOT rely on it anyways if you're just starting out,and to transcribe every sound you've ever heard in your life."
(Jazz musician here) I found the OP's "I’ve never learned to play sheet music, and have no interest in it" strange - because for me, being able to write music is far more useful than just to be able to read it. (Although reading is super-useful also, whatever the genre.) I hear something I like in the street, or in my head, or on a recording - I write it down! the notes, rhythms, harmonies. How do you do that if you can't "read music"?
Not to mention transcribing, i.e. writing out tunes and improvisations. When they're more than a certain speed, learning from just playing along with it becomes impossible, and you really have to write it down first before you start to play it.
Not really quite a few. If you look at the number of performers on that page compared to the total number of working jazz musicians, it's a completely insignificant percentage.
I have never met a working jazz musician who didn't read music, or, more fundamentally, didn't have an incredibly solid understanding of western music theory.
This is not to say the ability to read music somehow hurts your musical abilities. Sometimes thing are simply not that correlated. E.g. having an absolute pitch - does it help to become a great musician/composer? No one knows.