Apparently that saying means more than half your caloric intake from carbs? Sometimes even more. That doesn't sound to me like a moderate amount if I'm getting more than half my intake from it.
It's also commonly said to fit things like cookies and wine, but I never hear it used to include fats or even protein for that matter. The fact that people tend to respond with that tells me they know it's not doing good for their body, if it were why would they need to justify it?
Have you ever measured or a tablespoon of butter? Lol, silly question, I know you have. Have you ever done it in front of an everything in moderation follower and see the look of shock on their face as you put it in your coffee or eggs or whatever you put it in. Butter isn't given the same everything in moderation respect as chocolate chip cookies are. I guess so many still have that fear of fat they've been taught to believe their whole lives. So they much rather would like to justify three cookies that meet their macros than justify an actual serving of butter.