The story  posted by James Somers about their Rap Genius application stopped running on Heroku was a good reference which taught us not to rely on other platforms for a quick deployment even if the hosting platform provides benefits and is use to be reliable.
There is another story  about Twitter when they were using Ruby & Rails which had to be replaced by Java and JVM and it was not a trivial task by any means. People like to do a quick and dirty job so that they can see the results quickly. It's ok for prototyping, but be careful to go production with such implementation.
There is a third example  for not relying on third part tools. "You're giving them a throat to choke", it is said. If you have to use some tools, use as few as possible. It's not fun. After I done the research and investigation of the latest WordPress package, I have to dump it. Why? All of the effort is to make the web page responsive without coding. Is coding such a big deal for developers? That's the tool for businesses not for tech companies, even if it is just used as blog sites. You exchange your control and leave an additional layer of security threats by using the tools, See .