Man drowns at Point Reyes when fishing waders fill with water

There’s a huge difference between a static swimming pool and the water dynamics of currents, wind, waves, rivers.
And if you wear separate wading boots (especially heavy lug soles or cletes), the extra weight can make you negative buoyant—or, at least make it hard to stay afloat.
As far as kayaking in waders, good luck climbing back onto your kayak when they’re full of water.

Same for flipping over on a kayak wearing waders. People have enough trouble self rescuing themselves. The added water weight can be a death sentence.

I've flipped my kayak wearing waders (on purpose) multiple times. If you're wearing the right sized waders the top opening is just under your nipples and well encased in your PFD. If your waders are closed tightly at the top and your PFD fits you correctly then hardly any water will get in them when you go over. Even when I got smashed in the surf at Muir I only had about a cup of water in my waders and most of that was wicked in through the shirt I was wearing.

Same thing happened when I fell out of the kayak which flipped completely over. I was wearing neoprene waders with a Kokatat top and PFD. My problem with the waders was that, although the Neoprene kept me buoyant, I had a difficult time getting my legs below me in order to try to flip the kayak back over. An NCKA float tuber came over to pull me and the kayak to the shallows so that i could stand up. Only had a couple of cups of water inside the waders.