But you're mixing things which are regular maintenance with things which are a larger repair job.

It almost feels like you're saying the mileage a car lasts is about how many miles it can last without maintenance?

Adjusting valves (on cars that need it) is a regular maintenance item.

Cat converters, timing chains or belts are also maintenance items. Same for bushings, hoses, seals. None of these are a big deal. (Well, a few seals might be, depending on access).

Valve stems and crank bearings are a more major engine rebuild. I've never had to do this on any car even into the 200k-250k mile range. But if it is necessary, the car is back on the road after that, so it still "lasts".