All domestic white appliances have a design life of 10 years. Generally spare parts are available for 10 years.
Obviously there is an enormous variation written into this. DH managed to source spare parts for a 20 year old cooker, but it wasn't easy. Manufacturers also price spares to make it not worth while to repair appliances so that consumers decide on replacement instead.
When the heating element on my dishwasher went and I found a replacement element cost about £100, which sounded excessive for such a simple part. I did a bit of research and discovered that, generally, replacement elements were priced at a third of the cost of a new appliance. There was no relationship between the size/power of different heating element, only between the element and the price of the new appliance. With the cost of fitting, a new element cost half the price of a new appliance to replace, so most people replaced the appliance.