I don't necessarily disagree, but as a parent you have to be careful what you say to your kids because (particularly when young) they are prone to repeat it to the worst people at the worst possible time.
If my sister was constantly making up fantastic stories and I told my kids privately that she was lying, I'd be better off saying it to her face because when my kids tell her (or someone else in the family) what I said, it will be a disaster and the kids will end up in the middle of it. At least a direct confrontation keeps the kids out of it. But, it better be worth tearing the family apart because that is what would happen.
Yeah as with many things involving kids it depends on knowing when the kids are ready to understand - perhaps going from exaggerating to stories to lying to absolutely full of shit.
I’m sorry that gave you the wrong impression.