A Brita water filter lasts about 100 gallons, so this is a piece of paper with about a quarter of the lifespan of a traditional water filter. I'm guessing that the 'piece of paper' part of it is to make it cheaper and more easily transported, so as long as you have at four pages in a book, it's probably going to last longer.
What's the point in spending a week looking for patents on a technique that will take 5 minutes to come up with and 3 hours to implement, especially since you still have to spend those 5 minutes recognizing and coming up with a solution and the 3 hours of implementation (since patents don't include implementations)?
Religious laws in the past were actually subject to a lot of the same kinds of evolutionary pressures as genes themselves, and thus societies often end up with a set of practices that are by and large neutral or helpful. Sure, you have a lot of useless crap and even some harmful crap, but it's a pretty clever way of figuring out the world absent rigorous scientific models. The problem is when those practices interfere with further cultural evolution.
Even if it's just luck, that doesn't mean it doesn't merit study, especially if some portion of the practices show promise. Imagine if we were able to turn acupuncture into a practice that actually has some science behind it. Real medicine could gain a new tool and people in general can be better protected from Charlatans.