This is more related to how you deploy PHP or Python to the languages themselves...

Well, PHP is specifically optimized for that usecase, with opcode caching etc. Python doesn't do well when initialized on every request.

isn't this what pyc's are? what's the difference?

It sounds like they're talking about deployments where a new process is spawned to handle each request, but for the most part no one deploys Python web apps that way, so I'm not sure.

PHP may have some advantages in terms of deployment, so I guess it's a question of whether those advantages outweigh the potential advantages of using Python for development, which is of course subjective/situational.

It's because PHP uses a CGI process-per-request style model, while there's no good or modern for support in Python for that execution model these days (the community is built around WSGI and ASGI instead). Opcode caching isn't actually relevant because PHP reuses the processes and in-memory structures these days as much as possible.

Have you ever dropped a frame while debugging and fixing it on the fly in a debugger?

I think you miss out if you feel that this is a win when doing PHP.