I don't think it is that deep.
You foot constantly wears out if you to barefoot. It regenerates its own skin and heals. Dead materials don't do that. In order to survive thousands of kilometers if 60-100kg of weight (x2-4 of force) you would essentially need a material harder than whatever it is exposed to.
Way before planned obsolescence was even a concept, cobblers were an extremely common profession, specifically because there is no material that can simultaneously be soft enough to dampen force going into the foot while being hard enough to not be worn out scraping against rock, dirt, and sand.
Absolutely 100% the average shoe now lasts significantly less long than 100 years ago, but even then, people would definitely go through a dozen pairs of boots and shoes in their adult lives. Back then, they would just get the sole replaced.