A company I used to work for partnered up with a large Software as a Service provider years ago (when they were a bit smaller). We along with other companies were writing applications to work with their software, and the Service provider was happy to have all of these applications to offer with there service. Turns out that they would find out which ones were most popular and then copy it which would put the integrating company out of business. Fortunately for us, we saw the patten early on before they had a chance to do it to us, an we left them.
Proof that this does happen. The provider today does not get tagged as an evil company, yet it does this.