Edit: which mysteriously doesn’t appear to link on my end.

https://en.wikipedia.org/wiki/Demographic_history_of_Palestine_(region)

Your timeline would almost certainly be a little less stupid if you did that with gusto, but people who’ve disagreed with you can also post things beneficial to you or post insights you hadn’t thought of or post advice you’d find useful. I was a heavy RES tagger on reddit and I’d often come across well-meaning or useful posts and comments from people who’d been marked for saying jawdroppingly stupid shit about some other subject.

I know in your example you’re trying to give the right answer or explanation as you see it, but this is also very closely related to Cunningham’s Law:

The best way to get the right answer on the Internet is not to ask a question; it’s to post the wrong answer.

So you’re still providing a service even if it feels bad to have an expert steamroll whatever perception you had. Chances are tons of people had the same vague notion as you and your misguided logic eventually led to the correct path.