Lots and lots of people do web stuff in Python. There are a whole bunch of Python web frameworks like Django, Pylons, Flask, etc.

And there are big sites written in Python, too. Reddit, YouTube, some Google apps, Spotify, Netflix.

Rust is still a bit young, but also has several web frameworks like Rocket. No big case studies that I know of, but Rust still has many more fields of applications than PHP does.

people aren't doing web stuff in python?? django, flask, etc. are still very popular. maybe not as much as a few years ago, but people tend to stick to tech they know well, and python's web libraries are pretty battle tested at this point.