The reason we're talking about throwaway economy is because quite often, the parts that fail are not available in any reasonable quantity (phone screens, appliance motherboards), and paying for repair (or acquiring them yourself and doing the repair on your own) costs about as much as a new device. At which point most people rightfully ask, why bother?
Also, when comparing to 1960s - 1980s, one has to remember that it's not just that the devices were simpler then. They also often came with technical manuals, and they were intended to be home-repairable. OTOH manufacturers today seriously screw up repairability even when not necessary. I get that screens are best made as fully-integrated parts, but compare e.g. Kindle 3 Keyboard, which is as close as you get to swappable screen (pry it open, screw out some screws, pull the screen out...) vs. devices which are internally glued together, so that trying to take it apart risks destroying some components.