Another factor for disc brakes, other than packaging them so there is no contact when the bike is folded, is that the smaller the wheel gets, the closer to the ground the disc is. Come off a curb at an angle or kiss a rock while off road, and your disc becomes a fender.
I run classic side pull callipers on my classic folders on steel rims, and no they are not going to stop me like a train but they do require little maintenance. My point is that the harder you push your equipment, the heavier and more complex it becomes, and the quicker everything will wear.
If your rims are wearing quickly your choices may be:
- create a heavier replacement
- create a lighter more complex replacement that will need more servicing
- change riding style
- change machine
- treat rims as a consumable