But why would I bother to do that when I see no reason to suspect that there is any possible benefit to riding in a manner that seems (by my observation at least) to be only used by people who can't ride well at all?
If the OP wants to ride that way that is fine with me, but I see not the slightest reason to suspect that there might be a benefit to it.
Because you gain nothing by assuming. Assuming only opens up the possibility that you are wrong. By choosing to not assume anything you gain the possibility of learning something new (if the evidence is presented to you) without the risk of being wrong. Choosing to not assume anything has every advantage over assuming without sufficient evidence.
Of course, I understand why you wouldn't want waste your time testing a result which will probably be negative, but that's no reason to assume the opposite result. Choosing not to assume anything isn't any more bothersome than assuming.
Nope, you're wrong. Assumptions can save your life. It is natural and instinctive to assume. We wouldn't have made it past the stone age if it weren't for our ability of assumption.
Let's say you were a tribal person living in Africa and you see some fearsome looking strangers from another tribe coming with spears in their hands. Would you assume that they are coming to kill you and your people and take defensive action or would you just kick back and not assume anything until they show you what they want?