It also has to do with your tolerance for dog fur as a condiment. A boat is a small space and dogs with fur that blow coat like labs can generate a lot of extra hair. Dog lovers don't even notice of course. The food just don't taste right without it.
The hair dogs of course don't have that problem but the breed selection is more limited.
Some folks train their dogs to go on a piece of AstroTurf on the foredeck. Then just troll it in the wake of the boat to clean it.
As you can see you have to get a wheel boat if you want your dog to steer for you. Dogs prefer wheel, monkeys prefer tiller, or so I've heard.