Why do people who are also on the internet always feel like trying to say the other person doesn't go outside is a valid argument it's just as likely you're a basement dwelling virgin who hasn't seen the sun in months as it is he is.
I get what you were saying and what the other commenter was saying. You're saying that no knowledge is inherent, all knowledge needs to be learned.
The other commenter was conflating common sense with common knowledge, being knowledge that the majority of people know and can recall (but would still need to be learned at some point from somewhere).
I don't think you are wrong, and I think the other commenter was trying to say that common knowledge changed over time (true). I hope neither of you let it affect your day too badly.
But by creating isolated communities, the common sense will be isolated alongside into clusters of uncommon common senses which will make them not common at all.