I think "you don't know what you're talking about" is
substantively different than "in my experience, you are wrong about this". Firstly, lots of people who do know what they're talking about are wrong about lots of things. Making it about the person instead of about the thing was (for me) the problem with your comment. Also, "in my experience" is not just polite fluff. I have come across diminishingly few things in computing that are not dependent on circumstances.
The interesting version of this conversation would have been you saying, "no that sounds wrong to me", followed by a discussion of (to the best of your memories) what kind of hardware, drivers, kernel and compiler versions, etc. you were each using. Maybe you would have convinced me that there is no combination of those things for which the original commenter's experience could possibly have been right. But your throwaway ad hominem comment didn't, and couldn't ever, accomplish that.