I was big on Rails scene when it was huge in 2008, and saw a big exodus from it. I found so many of the "Rails" problems were solved by learning two languages: ruby, and sql. People would go to crazy lengths to avoid looking at the queries they'd actually run. I can admit to not really learning ruby as a language by itself, and can now see how much better my old code would've been if I wasn't just blindly shoehorning Railscasts in there.

Similar problems for people who learned angular but not typescript, laravel but not php, etc.