It unblocks that workflow, that's why it's so great. You can have a single script with inline dependencies that are auto installed on execution. That can expand to importing other files, but there is very little setup tax to get started with a script and it does not block expansion.
It's not about single-file scripts, it's about having a "sandbox" environment in which various things can be messed with before abstracting anything out into a project.
This is a divide among different Python devs it seems. A lot of people are running scripts, which I will do eventually, but I spend a ton of time in a REPL experimenting and testing.
Yeah, it's this experiment-first workflow that's not so well supported.