students who struggle

I've just noticed this wording of a Core Finding listed on the Math Panel's 2-page fact sheet:

Explicit instruction for students who struggle with math is effective in increasing student learning. Teachers should understand how to provide clear models for solving a problem type using an array of examples, offer opportunities for extensive practice, encourage students to “think aloud,” and give specific feedback.

National Mathematics Advisory Panel

Explicit instruction for students who struggle with math ----- that population is approximately half of all students K-12, right?

If students who struggle with math need explicit instruction, it's hard to see where school districts can justify adopting constructivist curricula and then supplementing or remediating with Pinpoint Math and the like.