Are patents a necessary evil?
I don't think patents are inherently evil, however they certainly can be used for evil. But The basic idea is sound. If you invent a novel mechanism and publish it the government will grant you exclusive economic exploitation rights to that mechanism for the next 25 years. After that it is now fair game. It is an attempt to solve the real problem that it is much harder to be first than second, the guy in first place…
The problem is that patenting something doesn't require one to put a lot of time and effort - just to produce few pages of text and diagrams. So it might be sufficient for somebody to have a general idea.
Then 25 years is too much.