Appliances are rarely retired because the structure failed. They are retired because one specific component became unavailable, undiagnosable or uneconomic to replace.
Parts supply has a finite window
Manufacturers stock service parts for a period after a model leaves production, then wind that inventory down as demand from repairs falls away.
Once factory stock is exhausted, repair depends on the aftermarket, on salvaged units or on a superseding part that fits. Some components have no substitute at all.
Control boards age worst in this respect, because they are model-specific and cannot be fabricated locally the way a bracket or a hose can.
Diagnosis requires information as much as tools
Modern appliances report faults through error codes, and interpreting them requires a service manual or diagnostic software the technician must obtain.
Where documentation is restricted, a technician resorts to swapping likely parts, which raises the cost of the repair and the chance of replacing something sound.
Right-to-repair laws in several states have begun requiring broader access to manuals, parts and diagnostic tools, though the scope and the covered products vary.
Labor economics set the threshold
A service call carries a fixed cost before any part is fitted, and that cost has risen faster than the price of many mass-market appliances.
When the quote approaches half the price of a new machine, most households replace instead, and technicians know this before they quote.
The result is a threshold effect. Inexpensive appliances become disposable not because they fail sooner but because the repair math never works.
Design choices make some repairs impractical
Sealed assemblies, bonded housings and proprietary fasteners reduce manufacturing cost and improve reliability while making component-level repair impossible.
Where a bearing was once pressed into a replaceable housing, it may now come only as part of a larger assembly priced close to the whole machine.
None of this is necessarily cynical. Integration is often cheaper and quieter, and the repair consequence is a side effect rather than the goal.
What extends service life in practice
Appliances built on widely shared platforms tend to stay repairable longest, because parts serve many models and the aftermarket has volume to justify production.
Independent service networks matter too. A model with no local technician trained on it is effectively unrepairable regardless of parts supply.
Asking about parts availability and local service before buying tells a household more about likely lifespan than any published durability claim.