It does seem odd, doesn't it. However, their PPS is really low (zero? .000001... who knows) so they are making money.
I have never understood the stinky pinky world. Logically, it doesn't seem to make any sense but it is a money making machine, that's why there are so many scams out there, MYDX amongst them.
Certainly MYDX would like the PPS to go up, more money for them, but then that would require real work.