Just idle speculation, but I would hypothesize that part of the reason some people are able to "bend the rules" or act "aggressively" in the context of frequent flyer programs (and I have occasionally done so myself), is that their actions seem neglible and largely without harm.

For example, the actual number (and the value) of the miles involved is typically small, the individual has probably paid a significant fare to the carrier for that trip (or in aggregate), service levels leave many feeling that they are not getting their dollar's worth, and the airlines seem to represent the bad guys, profit seeking at the expense of the needy (i.e. US).

If the cost of one's actions regarding these programs were identifiably greater, the cost and returns closer to even, the customer had a greater feeling of satisfaction, or the "victim" was a more respected or empathetic group, then you would probably see even less of this behavior occurring.