I'm the author of the original piece. Totally agree with this -- it can be quite simple to implement. Increasing retention makes a big difference. Unfortunately, there are more incentives to hire than to retain, so many companies do a poor job of it.

I've been at three companies that have implemented pay equity (and one of those I was the one implementing it). I wrote up a guide to implementing pay equity here: https://www.rubick.com/implementing-pay-equity/ and it's basically as you describe -- have new and existing employees get paid the same rate, with no manager or recruiter discretion.