Because first is Sony ... they are weird for the good things are for the bad things, second if you have something which is
ahead in the roadmap of AMD you cannot talk about it, the NDAs also apply to Sony.
I don't think there's a possible NDA over a released product.
They wouldn't show up in Q3 2021 saying "you purchased this hardware 10 months ago, but we couldn't talk about it".
I don't rule out the idea of the PS5 having a nice custom feature. But they should be able to tell about how special it is.