Is it really so obvious that small N is statistically insignificant? Stat sig is a method to empirically improve knowledge. Well, if it's intuitive that you need high N to get empirical knowledge, let's try an intuitive example.
Say you're a tribal chieftain. One of your men (one among thousands) finds a berry bush. Another eats a berry from the bush. He promptly dies. You're a scientific tribe, though, and you know N must be high before you conclude the berries are poisonous. So, one of the other guys eats another berry. He, too, dies immediately. The process repeats until it's you considering the bush. How does the situation change if the number of people before you was 19 vs 21?
Say you're a tribal chieftain. One of your men (one among thousands) finds a berry bush. Another eats a berry from the bush. He promptly dies. You're a scientific tribe, though, and you know N must be high before you conclude the berries are poisonous. So, one of the other guys eats another berry. He, too, dies immediately. The process repeats until it's you considering the bush. How does the situation change if the number of people before you was 19 vs 21?