It's more of a "clever use of PPS mechanics" rather than fraud because everyone profits from this.
Filesonic profits because they sell accounts which otherwise wouldn't be sold (maybe).
The buyer profits because he pays less.
The seller profits because he keeps a % of the sale.
Generally, it's a win-win situation and those who might loose a few bucks are probably the uploaders. Then again, the same happens with the premium referal link. The only difference is that the seller keeps a lower % of the money. On the other hand, methods like this guarantee a strong marketing network spread around the web aka, plenty of $$$ for Filesonic B-)
However, i agree that this should not be allowed because i'm sure that some people are so greedy that would probably abuse this mechanic at the expense of others. If there was a way to prevent any possible abuse, i wouldn't mind seeing people doing this thing in order to promote sales
