Not sure about the productivity claim. I once wrote from scratch (frameworks excluded) backend and frontend (version 1) of a multi-tenant, cloud-based video-sharing platform with PHP as the backend (aws cloud) in a matter of weeks.
I once wrote, from scratch (frameworks excluded), an entire backend (and front-end) of version 1 of a hybrid mobile app (backend in PHP) for a medium-size logistics company in a matter of less than 2 months.
I have other examples, but life is too short trying to convince "haters" that they might not be 100% correct.
I was the only developer on both of those projects. Your mileage may vary :)