Yes. Exactly. It omits future network calls (things that have not yet happened by the moment you look), which is what the person you were replying to was talking about.
You won't be able to see that activity until after it has happened. An empty network monitor list isn't a guarantee of future behavior. Or current behavior.
> You can, in fact, use the network tab to monitor a page's ongoing network activity as originally suggested.
Did you forget that this comment chain was about leaking data to the server? Observing that you have leaked (note: past tense!) your data is not a recommended way to prevent leaking data.
I am sitting here looking at a new entry added from a button click that creates a network call. Either you are wrong or confused about what the discussion is about.