That is, in fact, not correct. Yes, there are things that have thresholds where they are harmless (e.g. salt), but alcohol isn't one of them. Alcohol, like many other toxic substances, does not have a threshold below, which it is harmless.
The WHO says the damage starts from the first drop: https://www.who.int/europe/news/item/04-01-2023-no-level-of-alcohol-consumption-is-safe-for-our-health