Earlier quoted context omitted.
Professors who fail large swathes of their classes get in trouble.
That is the entire problem in a nutshell. You cannot reject more than one or two students in a year or the school will reject you.
This is a silly perspective, but the blank slate folks really got their tendrils in just about anywhere. In reality, some people are simply bad at math. More education will help, but they will always be disadvantaged compared to people who are more naturally predisposed. (note, I'm quite bad at math myself)
It may seem altruistic to err on the side of caution here and try to catch the kids that fall through the gaps, (again, assuming that they are falling through the gaps due to systemic failures) but as the article points out, there is a limit to this approach; eventually it brings the talented students down and degrades the program.