It’s not the feathers exactly, it’s more the types and arrangements of the feather types are different. Owls feathers are waterproof from rain and snow, but they’re not set up in a way to deal with a thorough soaking like getting a bath like this. Something like a duck or other water bird is structured to withstand that type of environment.
That’s my understanding anyway. This seems an area where amateur bird people seem to confuse some things with different birds species and there is much conflicting and incorrect information floating about, so I try to avoid this topic since it’s an area I know I don’t really know much about.