@jon I don't really see those problems for my bikes.
I can get manuals with part numbers for my bikes, wheels, and accessories
there are large online shops who will have these parts
many good guides on how to fix stuff from park tools & co, or just random YouTube videos.
It can be expensive, especially if you need specialised tools.
Some parts are not made to be serviced at home, by design. I am especially annoyed by Bosch motors. I hope future right-to-repair regulations will help.