This means absolutely nothing. Otherwise everyone would be using Haskell, Coq or Agda. I'm willing to bet your favorite language has an insane amount of flaws a

This means absolutely nothing. Otherwise everyone would be using Haskell, Coq or Agda. I'm willing to bet your favorite language has an insane amount of flaws as well (hint - they ALL do, otherwise we'd have converged to the "one true language" as an industry long, long ago.) You can make an argument to say C++ is terrible, Java is, Ruby is, Python is, and it means absolutely nothing other than showing of your own insecurities. You can build great and mediocre things in any language and any platform. People do every day. Also, if the developer is not one of the users of the software, you've already thrown a good chunk of quality out the window right there. You're simply not going to have the vision required to build the optimal user experience.