Yes, the original anecdote was simplistic. Most “anecdata” is.
However your response that their social anxiety wasn’t a result of their upbringing, and then expanding that with the evidence being your own anecdote, is far more simplistic and somewhat uncharitable too.
You might be correct but you might also not. However you know less about the situation that the commenter (obviously) so I don’t really see how you can confidently assert anything about their condition.
And that is why I responded the way I had. It’s not saying you are definitively wrong; just that you know far too little about the specifics to make assertions.
However I am glad you’ve found your own path to zen.