Any example of high SNR authors who consistently putting more than 2 papers months after months after months for this to be a problem?

It doesn't seem humanly possible to produce >2 "high SNR" papers per month. If you have a larger batch of related papers, it's easy to spread submissions over multiple months. You should probably be doing that anyway, because comments on one paper may affect the others.

Do you have a concrete example of a high SNR researcher who will be limited by this policy? Aka one who is submitting more than two high quality papers per month?

I imagine they could augment it with giving higher rates for some people based on things like h-index.

It's pushing slop elsewhere.