What's a different path to the solution of getting a kid to eat vegetables and go to bed? I'd say if you can get them to freely choose to do those, then you've won the argument. If it comes down to the equivalent of telling them "because I say so" in such a positive and constructive way that they don't freak out, you haven't won an argument. You have gotten what you wanted, but not by winning an argument, because the kid's opinion didn't change, just their response.

Now, what you're talking about is an extremely valuable skill—much more valuable than trying to argue with toddlers—but it's not the same thing in my opinion.