"Some of the real epoxies penetrate very deeply into certain woods"
That is rare, in my real world experience of tens of thousands of square foot of wood/epoxy laminate. If it is critical I get a coating I use a light cloth to assure a coating thickness. The 'water resistance' is not totally in the epoxy but one of the additives, Mica, which lays flat in little layers of plates causing the water to have to work around the Mica plates AND through the epoxy.
"You need some for humidity expansion etc...IMO."
I don't share that view and neither do the formulators and proponents of full epoxy encapsulation. It is a real PITA to seal every edge of a set of blades, pre-drill then drill oversize the bolt holes that will hold the blades, inset plugs or fill the holes with a proper epoxy filler, re-drill the holes and track the blades and then finish covering the blades and coat, sand, coat, sand ........ until the blades are smooth.
Then, all of this pretty work needs to be painted. Don't worry though, if the machine is properly mounted, high enough, it will be hard to appreciate 'bright finished' blades.
There is a LOT of labor in properly epoxy coating blades. It is also at the tail end of a project when everyone wants to get the machine flying.
Ron