Alice shows some code to Bob. Something about it catches Bob’s eye; he tells her that this mechanism is a bad idea and she should find another approach. She asks why.
Bob, despite being correct, can’t answer.
Or maybe he can, but is worse off nonetheless: for every pitfall or potential consequence he dreams up, Alice fires back with how she’ll compensate or why it doesn’t apply in this case. Eventually Bob runs out of ideas, and Alice carries on with what she’s doing, now feeling more happy about it—she’s fought for her work and won, after all.
Bob is arguing from principle, and Alice is scoffing at the idea of principle for its own sake. Principles are for academics; out here in the real world, whatever gets the job done is good enough.