You have a firm belief that "wear is wear" is relevant above all else, and therefore, to you, wear holds up to scrutiny. But all one has to do is look at the ancients market to see that it is not universally accepted as true. Severity of surface conditions, strike, luster, eye appeal; these things matter. Whether a coin has or has not circulated is wholly irrelevant, and the exercise of squinting at coins to determine if it is an AU58 or MS66 is one of the most misguided aspects of numismatics. Take a coin, a perfect coin. Any contact mark, friction/wear, hairline, or scratch reduces the state of preservation of that coin. It does not matter one bit how or where the detrimental surface condition got on the coin. As you say, there is no way to tell anyway. Any detrimental surface condition (yes including wear - it is not special!), depending on severity, lowers the state of preservation of a coin commensurate with the severity. Period. That's all you really need.