Outside warranty processors

I've been wondering what the 'taboo' is with outside warranty processors. I had dreams of working from home - made a nice professional package to sell my services - yet was shot down by everyone I approached with no actual reason given. I always a "we'll think about it" with no return call - when I call back they say the factory is against it. I scoured P&P mannuals and none of them say anything in regaurds to outside processors being a bad thing. They are pretty much written as though dealers should process in house, but don't say not to. How do you guys feel about them? Has anyone had a bad experince with one? Just looking for some insight.