Currently if you type an ISBN it links to the book sources page and gives you a variety of places to find that book. To link to a patent, you use one of the patent templates, which can only link to one place. The official US patent office website has different functionality from, say, Google Patents, and they each have their own major benefits and disadvantages. It would be best if a page like Book Sources was generated automatically from a patent link, too, so you could follow a variety of links. See discussion in link.