>Thats pretty much what a Pull Request is.

Then you have to use email for the review conversation, make the discussion easily available to everyone involved and future devs, track manually which comment refers to which line of the diff due to lack of overlaying, manually ping to warn of updates, rely on manual quoting, no direct information on whether the CI pipeline succeeded...

To me that feels like writing code using only sed. It is possible, but it removes or makes convoluted an absurd degree of regular work.

You are correct, but integration with CI/CD and other services as a part of pull-request process in a modern platform is very convenient. I would not go back to e-mail. Especially since I can self host the whole platform like Gitea.

And the discussion about that PR goes in an email chain too?

You can pull, but having the back and forth documented along with the code is not a nice to have imho