I’ve hunted in a lot of wet weather, a drizzly light rain day is great hunting weather. These days I hunt with a selfbow most of the time and use a side quiver that protects the fletching. If I’m in head high drippy brush or a heavier rain I cover the top of the quiver with a camo nylon bag with drawstring. If I use a bow quiver I cover the fletch with the same bag. It also covers bright fletch when using a bow quiver.
Agreed that natural feathers have more oil content and are more waterproof. Commercial feathers go through washing and processing.
On the subject of feathers, is everyone aware that steaming will renew your matted feathers. Often feathers that have been messed up bad can recover with a steaming.