Well it's statistically likely that the students who don't do well on reading comprehension might struggle with other things too, but it's not like reading is n

Well it's statistically likely that the students who don't do well on reading comprehension might struggle with other things too, but it's not like reading is not a foundational skill for being able to do well later in school. One outlying example is dyslexics - one can be arbitrarily bright, but have enormous difficulty reading - I've personally known extremely intelligent people who struggled finishing high school because of their poor reading comprehension - this is something that ought to be remedied. I'd say it's far more likely these students struggle academically - but the problem is that the further they fall behind, the more of an uphill battle for them to keep up with the class, let's say X takes 50% more time to solve a text-based math problem than his peers, but due to his poor reading comprehension he takes again 50% more time just to understand the problem - which might make the difference between failing and passing. And as lacking as public schooling is, I'd expect them to do their damnedest that people leave school with at least basic reading comprehension after 12 years of education.