Because, last time I checked, your mom's PC didn't have a Bitcoin ASIC in it.
Same is true with GPUs. Never seen a botnet of 5870s. Whoever is geeky enough to buy a 5870 knows how to be secure usually.
Quit the marketing and BS talking. You are not using custom ASIC as that requires millions to produce and nobody would take that risk.
Probably using sASIC in the best case ...
it pretty much says that the current offering is based on sASIC.