I don’t think the presence or absence of guards makes much difference to drive/hub wear rates really.
OK mucky water may accrue on the inside of guards and drip back on to the wheels and drive but the majority will be promptly centrifuged off again, some will inevitably migrate into the drive parts and general road spray gets to everything eventually and causes wear, versus a pretty constant stream of mucky spray from an unguarded front wheel backwards, directly onto the BB and drive same spray from an unguarded rear wheel over the BB and front mech as well as all over the rider…
Ride in the wet and the parts will get wet, guards limit how wet and cold the rider gets, IMO that’s their primary function if you don’t want to maintain a bike through winter there’s always the turbo trainer.