[averagefluid]

Market-based hypothesis is that the person erecting the fence incurs costs and if the expected value of the fence isn't higher than the cost of erecting it, it wouldn't have been erected in the first place.

Of course mismanagement happens but the implied value of understanding why the fence was erected is to understand the expected value it would bring and understand the problem it was trying to solve. This does not imply that it should have been erected, just that there were others before you trying to solve a problem and if they're failing it's important to know why so you don't fail in the same way.