MoneyPaks can be reported stolen/whatever and be reversed.
Also, if any shady business comes up with MPs (For instance an MP being reported "stolen" after it's been loaded to a PP account), MP will sometimes blacklist that PP account, leading to problems for people trying to do business with MPs. Happened to me. My PP account can no longer receive MP loads thanks to some scammer. At this point your only option is to request a "refund check" from MP, which takes a week or two to arrive. Naturally, if someone reports the MP "stolen" during the shipping time, MP will cancel that refund check.
So all in all MP can create problems.