Folks use "python -m myproject.mymodule" to run code that they're working on all the time - it's currently the only way to get sys.path right for cases like that (otherwise you're exposed to the double import trap, where you can get two copies of a submodule under different names).

We even use it to run CPython's own test suite as "./python -m test".

That said, over in https://bugs.python.org/issue33053#msg314192 I came up with a plausible migration path away from doing that implicitly - we'd just have to introduce a spelling for doing it explicitly instead, and relative imports give us a precedent for that.