The appliances of 25 years ago bear little resemblance to the appliances of today. Take a washing machine or dryer, with an electro-mechanical timer. Lots of electrical and mechanical parts, all of them replaceable or repairable. There were a few timers made by a few suppliers to supply nearly every manufacturer's washing machine. Today's washing machines are far more complex, and like nearly every other appliance from laundry to kitchen, has a control board. If the control board fails, you are generally screwed. They are often quite expensive and there's no telling it will solve your problem...could be one of the myriad sensors.
While some appliances can be fixed, that doesn't mean they should be. Take a builder's grade dishwasher that's 15 years old and failed because of the pump or similar. You need to completely remove the dishwasher, turn it upside down, remove the pump, find a new pump and re-install. You are easily looking at $200 or more in labor (for those that have to hire a pro), not to mention the part. The GE WD26X10013 Genuine OEM Pump and Motor Assembly used in a ton of GE dishwashers made in the past 50 years costs about $200. Even if you do the job yourself, are you going to buy a $200 part to put in a 15 year old dishwasher? Makes no sense. If you have to hire someone to do it, the best advice is to replace the dishwasher. The GE dishwasher in my new home "failed" when just two years old. Looking up the fix for the symptom (telling me the door wasn't closed) I saw a common issue with the switch interlock at the top. I bought the new part ($26) and replaced it. Didn't solve the problem, so I was out $26 plus days of waiting and hours of labor. Thankfully I "parted out" the unit and made a few bucks to help defray the cost of a new Bosch 800.
A 25 year old electric range can also be easily repaired. A new one? There's that control board thing again...If all your [electric] appliances (except a microwave) are 25 years old, you can probably keep them going forever.