Design For Obsolescence isn't often the goal ... just a side benefit. Not that it doesn't happen.
The goal is usually something like: ensure we meet durability requirements X, while minimizing costs.
Now in practice that might very much amount to the same practical impact, such as the product will break after the designed lifetime, but maybe not if it happens to be cheaper to use a simpler, cheaper component that actually is more durable. But probably there is some component that is the weak link that only meets the minimum design specs. And this yet one more reason why Repair is important, because many of the components are perfectly fine!
The goal is usually something like: ensure we meet durability requirements X, while minimizing costs.
Now in practice that might very much amount to the same practical impact, such as the product will break after the designed lifetime, but maybe not if it happens to be cheaper to use a simpler, cheaper component that actually is more durable. But probably there is some component that is the weak link that only meets the minimum design specs. And this yet one more reason why Repair is important, because many of the components are perfectly fine!