It's not half and half. It wouldn't be nearly as bad if it were. The unfortunate fact is that it's the vast majority. And that that vast majority carry on in complete ignorance of their ignorance. With some, of course, they are such bad listeners that putting the dots down and only using their ears wouldn't make a jot of difference. (I won't name an example, 'cause I'd only get "moderated"). But quite a few, I believe, would benefit a great deal from it.