I have been developing paid software projects since 2003. Everything from C, Perl, Python, PHP, Ruby, Go, Scala, Objective-C, Erlang, all the way to Elixir, and many more.
In the past decade i have consulted for everyone from small business up to fortune 500 companies and learned a great deal about various languages, frameworks and designs.
Building Web-Applications is hard. Making them scale is even harder. And nobody said anything about robust yet.