Here's how it's done, in simple terms. This is not some new thing. IBM was doing this before there was a Microsoft and before there was a WWW.
If you amass enough vague patents, any one of which on its own isn't worth the paper it's printed on, then automagically they no longer remain worthless. Suddenly you have something valuable: a patent portfolio! This is because it costs a significant sum to pay someone (e.g. a patent attorney) to go through your wonderful portfolio of junk and determine which ones are worthless. And that is in turn because patent law firms charge very high fees to do that work. And that is in turn because not every lawyer is permitted to become a patent lawyer - so there's only a limited number of patent lawyers - hence they have less competition to drive prices down. The uncertain validity of a bundle of patent claims that I can allege others are infringing is the value. Threat == value.
Therefore if I have several hundred vague patents of which a definitely large proportion are worthless and I sue you alleging you have infringed a significant number of them, you are screwed. Because it is going to cost you a lot of time and money to have someone go through each and every claim and convince me you are not infringing. So you just concede it's not worth it to fight me and my deep portfolio of junk software patents. And we start negotiations. Needless to say everyone at the negotiating table is not going to be in a happy mood going into this given that we had to start the whole process off with threatened or actual litigation. This is "business", American-style. A model for the world to follow.
