Only in America and even there that's only true in theory. In practice it is a lot easier to invalidate a patent with an earlier patent than it is to argue prio

Only in America and even there that's only true in theory. In practice it is a lot easier to invalidate a patent with an earlier patent than it is to argue prior art with a publication (this is, of course, depending on how the patents are written). Patents can also be used "defensively" in ways that prior art cannot. So it's not always just about prevention. Personally I think whole system could use an overall. Not just in America either.