That paper is specifically for C++ and even there not every body agrees (there is still a proposal to add stackful coroutines). One claim in the paper is that stackfull coroutines have an higher stack switching cost. I disagree, but also this is completely irrelevant in python where spending a couple of additional nanoseconds is completely hidden by the inefficiency of the interpreter.

It is true that stackless coroutines are more memory efficient when you are running millions of lightweight tasks. But you won't be running millions of tasks (or even hundreds of thousands) in python, so it is a non-issue.

There is really no reason for python to have chosen the async/await model.