I've had a lot of people on Hacker News very confidently tell me that I have no idea what I'm talking about on this topic. For a long time I thought I was just dumb, but still employed years later and have realized that most of the people that 'correct' me have exactly 0 experience.
(From someone who also gets defensive in online comments. I don't think they per say told you that you were wrong, but rather described their experience in relation to what you'd said. It seemed to me like commentary more than criticism. I don't have a crystal ball to tell me when people are exaggerating their credentials on the internet but they seem to be credibly claiming experience in this thread.)
I think if you feel like that’s happening to you the best strategy is to ignore it, but the second best is to prove your understanding. Explain with depth that can only be gotten from direct experience. If you know you know, either be confident in that or demonstrate it. I didn’t feel like you didn’t know what you were talking about though, I just thought you might be missing some nuance on the topic.