Rarely do pipes, wires, or ducts just outright fail even in 50 years. Usual case for tearing out drywall is for voluntary renovations. Shit behind the wall just doesn't "fail" if it is left undisturbed or you were unlucky like those that got defective PEX or similar installed.
My house is 150 years old, but it's also been rebuilt several times in that time. My neighbors' houses are less than a decade old. We have all swapped stories about replacing things behind drywall. Leaks. Electrical issues. Ducts. Everything. Consider yourself lucky if you have not. 50 years is not the number you should bet upon.
So outside of a few notable examples, the materials rarely fail, galvanized duct work should easily last half a century in a properly installed and maintained system, properly installed copper pipe or PEX and even (C)PVC, properly installed NM or wiring in conduit where code requires, where people get into trouble is with shoddy builders and the housing market often causes those to forgo proper inspections and it is ultimately a “market for lemons”. But blaming drywall seems a bit misplaced, since shoddy building in targeting cost only, they’re going to be the last ones replacing drywall with something fancy and expensive.
Wires not really but copper and iron pipes and ducts can and do corrode away. Ive seen hvac ducts that were more hole than anything but nobody noticed under the floor or above the ceiling.
About 15 years ago I installed a new kitchen faucet for my grandmother, whose kitchen had been renovated in the early/mid 90s. Right near the end of the time when PB was inexplicably popular. I have to say, I spent several hours cursing whoever decided to use PB, and in this particular case whoever decided that the pipes should connect directly to the faucet rather than terminate at a bog standard quarter turn valve. Lots and lots of cursing.
As I recall, wasn't PB basically a single vendor, too? Finding PB-to-anything-else adapters at Home Depot was like going on a treasure hunt. Sizing is different, so you really need something actually built for PB. And probably end up with sharkbites. If I were shopping for a house right now and found it had been plumbed with PB, I'd just turn around and walk away.
