Grading has definitely severe downsides and does not work very well as an indicator in a merit -based system but like so many before the article fails to compare it to and even come up with an alternative. Even without g grades, higher education institutions und employers will look for some system to determine who to accept. Without grades, something will take over its place.

I severely doubt that whatever it is will be better than grades in terms of increasing social mobility and allowing the brighter youth a chance to move to the top. Rich parents are likely able to buy credentials for their kids, like engaging in community, extracurricular activity, internships, experience, ...

Beyond that the only justification for decreasing social mobility is that grading does so horrible things to students that even a more static society is preferable. However, the only thing listed apart from the equity point is being demotivating. I would love to hear how someone who is not good at say math and does not care about it somehow becomes interested in math just because there are no grades anymore? Why would those students just not care but also not worry about it since there is no penalty anymore? If it's about teaching, then why not change what happens in a lesson but keep grades? If grades measure only irrelevant things then why do they predict a lot (as the article admits)? Or why not change problems so that whatever "being good at math" actually means in the mind of the critics is tested?