A lot of nonsense is swept in under this seemingly reasonable cover story. If I can't build a device that embodies my invention, in what sense have I really invented it?
I dislike patents in general and software in particular, but that one can invent yet not commercialize is not farfetched.
On the other hand, if Bob invents something, but chooses not to produce it, then he's effectively relinquishing his rights to patent protection.
When we allow Bob to simply transfer his "invention" (an idea basically) to Patent Corp. in exchange for cash, and Patent Corp then uses that to extort people, we massively incentivize dreaming up random ideas in the hope of getting them patented. That incentive exists whether or not the idea is a good one, practical, effective or any other characteristics that reasonable people use to evaluate things.
On the other hand, I think that software and business methods should not be eligible for patent protection at all.