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.
