The only appearance of 5,000 I can find is the following one in the Visual Studio 2013 Preview announcement [1].

»In that context, we have our Build 2013 developer conference this week in San Francisco, where approximately 5000 developers have gathered in person (with many thousands more watching virtually) from around the world to discuss the next generation of software development with platforms and tools from Microsoft.«

Maybe someone just confused developers and APIs...

[1] http://blogs.msdn.com/b/somasegar/archive/2013/06/26/visual-...