I think that figure is very skewed, like you said, except not “slightly”.
I know that prestige matters more in business than in engineering, but according to The Economist (I think? Either them or The Atlantic), it’s the second least prestige dependent field (behind engineering). So it can’t matter THAT much.
I’m pretty convinced all-around that any slight decline in prestige can be made up for with a slight increase in ambition/hard work. I don’t think any sane employer on the planet will pay you less just because you went to a lower ranked school (and yes I know some companies do that – I just don’t think they’re sane).