One of the biggest productivity boosts, even more so than the language is ecosystem and libraries. Having libraries that do json, interface to AWS S3, interface to Postgress/MySQL, OAuth, etc is a huge productivity boost, versus having to roll your own.

Many times in software development, more work is spent in glue code and wiring stuff together than actual algorithmic development. And speaking of algorithmic development, I would bet, that just about any common algorithm, and likely many esoteric algorithms have easily available, high quality implementations that you can plug into your code without too much hassle.