I’m sure that you understood the important differences, but there are likely many readers who didn’t (many more programmers are familiar with Python than with mypy). When you write “even if we don’t have P, we’d have Q anyway”, the reader is left with the impression that P and Q are somehow interchangeable or equivalent or comparable—that P is unimportant in the presence of Q. I think it’s instructive to point out that this impression would be mistaken, and the paper’s result of P is interesting and consequential.