You are comparing apples and oranges. Or, maybe, jerky vs. fresh meat. If you don't need long term storage, and rotating stock every two years clearly isn't, and the other attributes it provides, then survival rations, per se, make little sense. It's a product designed for a specific purpose and it fits that purpose well, a purpose that PB doesn't fit well, in the least.

As to PB not being thirst provoking, I'd have to say I definitely will have to disagree with that.

YMMV