Since people realised writing the same code in two different languages is a waste of time and the async-first nature of NodeJS/libuv is ideal for use in microservices.

Compare implementing back-end form validation in PHP and a completely different implementation front-end validation in JS vs using the exact same implementation on both sides. The former approach requires more work, creates a larger maintenance burden and a greater area for inconsistency and error because you need to maintain functional consistency between the two different implementations in the two different languages