Twitter launched Twitter Kit in 2014: a set of tools app owners use to integrate Twitter data and functionality. Since then, Twitter Kit adoption soared and Twitter increased its functionality. The v2.0 release constitutes the first major revision and a platform for expanded functionality and use.
Any company that makes an API knows that just having the API is not enough. A bare endpoint is probably worse than not having an API at all. To make your API and platform useful you need documentation, tools, examples and forums. If you are a successful API company you start developing a community of people that work with your service. The community shares ideas and helps each other out.