I don't think it is the only problem. Even if you learn the language and know it well, if you start contributing on a big project, it's going to be hard to unde

I don't think it is the only problem. Even if you learn the language and know it well, if you start contributing on a big project, it's going to be hard to understand exactly what happens and to be sure that you didn't make mistakes. At this point it makes sense to delegate some checking to the computer.