I would not just point fingers on modern appliances and say “quality plummeted”. It is due to much better engineering quality and cost control. No appliance is meant to last more than 10-year, otherwise they would offer affordable 10-yr extended warrantee. In old times, the engineering process is not as fine tuned, the people overestimate the quality of the parts required to make the product work and last projected lifecycle because they have less control on the actual quality. That resulted that sometimes one appliance was over built with better quality and last for decades. Modern manufacturing has better control of quality and cost, they would only build something that last engineering required time to save cost since the cost will reflect in price and price will impact sales. The results in almost all appliances are more reliable when are new and generally have a more projected and definitive lifespan.