I was involved in a company that heavily depended on a popular site's API. We could clearly see they thought of the API's best value for them as filling in feat

I was involved in a company that heavily depended on a popular site's API. We could clearly see they thought of the API's best value for them as filling in features before they had time to create them, and as a testing ground for ideas. It became harder and harder to stay ahead as our business grew, as at any time our features could be replaced with an official version. We decided to stop development. Now, a few years later our largest competitor has been doing quite well with a product along the same style... but now, without warning, they've been cut off from API access and are facing requests for hundreds of refunds. Glad it wasn't us.