Where do you get it from that a retriever cannot hunt upland?
On the other hand if somebody who knows about water-fowling dogs knows that the indeed good and shiny looking PP above has not the physical tools of the trade to work in harsh wet/snowy conditions around water and in swamps. No waterproof double coat, no webbed feet, no tail that can be effectively used as a rudder when retrieveng out of fast flowing water, the abilty to paddle along a kayak for up to 45 min. at a time...
RR
Um, PPs have webbed feet. And long tails. MY dog, and SCs, don't have double coats, but that's because we wanted slick ones. Look at Greenjeepguy's for a more typical PP coat. They are usually hairy, but they can also be short coat. Slick is ok, the breed standard is that it can't be too long. But most come out wire haired like GJGs, the slick ones can be looked down upon but dedicated upland guys tend to prefer them. Sure are easier to keep clean and cool.
I don't know what you define as fast flowing, but the tidal rip here is 4 or 5 knots or so, and Lola has no issue swimming back against it on a retrieve.
She's spent literally hours in the water swimming. Hours at a time. I don't go kayaking with her, but she does love swimming off our trawler.
Lola and I have spent many days each winter hunting snowshoes in wet and snowy conditions. Wet and miserable conditions. In cedar swamps.
As I said, I sure wouldn't pick a slick coat PP as a first choice for a waterfowl specific dog. Never. They're definitely not as hardy a retriever as a dedicated breed, but if you score the hunt/point/retrieve ability on land and water, they'll blow a retriever away. Duh. That's what very smart and very capable people have bred them to do.
And I most certainly did not say that a retriever CAN'T hunt upland. If you actually read what I said, I said the exact opposite. I said they weren't developed or specifically intended to do so, and any upland ability in a retriever is a pleasant side bonus.