The problem is that if you knowingly infringe on a patent, it's triple damages. So most companies that are big enough to have any budget aren't going to be allowed to use any product that involves them or anyone else searching through the patent database or using data from the patent database, since any record that they did so could result in massive legal liability.

There are about 15 companies in this space offering various services, but because of this issue the market has remained relatively small even though a lot of these companies have been around for a decade or more and have pretty mature offerings.