[Someone]

What would be your argument for getting budget to do that?

There are zillions of ways this hardware can break down. You can’t predict which ones you’ll have to handle, or whether there will be a way to recover from them. If you started researching this 30 years ago, and then something had killed this thing 20 years ago, that would be wasted effort.

Also, in the early years, they still could ask the original engineers, and even lacking those, there likely were engineers who hadn’t worked on this specific hardware but were somewhat familiar with this kind of hardware.