I don't know exactly what your definition of success is, but products of hyper-specialization do indeed make money. Etsy is eBay for home crafts, Twitch.tv is Justin.tv/YouTube/Ustream for video games. And of course there are thousands of enterprise solutions that are simply domain specializations of Microsoft Office and Dropbox that are doing quite well.
That is not true. 4 years ago Parse described itself as "A Heroku For Mobile Apps"