Defending against patent trolls is an aspect.

But the flip side is that this gives corporations a great tool to handicap competition.

If a competitor emerges, they can threaten legal action. And with a huge patent portfolio the big players can usually find a way to attack pretty much anyone.

Many companies will easily get scared and cave, and so either lose competitive advantage by dropping the technology, or feel forced into agreeing to an aqui-hire by the corporation . Which further cements the corporations dominating position.

This happens often enough, but rarely goes public.