Age-old alphabetic filing methods require that everyone (or at least a very special somone - like an administrator) follow rigid rules, select file names carefully and then remember how things are filed. The entire emphasis is on how you file so that you can find later. If you have staff turnover or if multiple people are accessing the same filing system, the system breaks down very fast and becomes, in many cases, relatively useless.
Paper Tiger uses a very simple method to put the focus on finding, not filing. The software is very flexible and allows people to find information quickly, regardless of how it was filed.