Because the designers of Go believed that most programmers at google are too stupid to understand and use them.
> The key point here is our programmers are Googlers, they’re not researchers. They’re typically, fairly young, fresh out of school, probably learned Java, maybe learned C or C++, probably learned Python. They’re not capable of understanding a brilliant language but we want to use them to build good software. So, the language that we give them has to be easy for them to understand and easy to adopt
How would you phrase this? Thinking programmers are too stupid to understand languages with modern features is just the plain literal meaning of the quote, no?
these same lowly colleagues were also incapable of wiping their asses at one point in their life but over the years and skidmarks, they all mastered that beautiful language and now make heated bidet money.
So a more charitable interpretation would be that most of his colleagues are in their 20s and just out of school with a CS degree. He doesn't think they can (productively) use the languages the cutting-edge PL researchers generate.
But trying to get new grads to use Haskell on the scale of a 10 million line code base, and have them not make a mess of it? That's the kind of thing he didn't trust the new grads with.
Even if you believe that anyone not capable of writing Rust or Haskell is stupid, it doesn’t mean that Rob Pike thinks that these people are stupid.