To answer your (rhetorical) question, it is common to file patents for moat-building purposes, i.e. to prevent competition. This is one reason lots of obvious and frivolous patents are filed, and why some companies have cultures that encourage filing as many as possible. There is not necessarily a direct return in the case where you stifle competition, (or threaten to), though it's good for the bottom line.

Alternatively, you have patent trolling which gets a return not through direct use of inventions, but through litigation. It's again not so much that the invention has value but that it interferes with value generation in a way that helps profits. Both cases are abuse of the system, and both cases are common. I'm sure those are the kinds of patents that GP referred to as "cruft."