You are 100%. With the internet the way it is now (the way we use it), it is almost inevitable for echo-chambers to exist. That is why it is becoming increasingly important to challenge ones beliefs. The only thing we as individuals and as a collective need to realize is that as much as we know, the only thing we can know for certain is that there is much we do not know. It is a bit childish to downvote, flag or censor something just because it challenges what you believe to be true or right. Frankly, it is immature. The mature thing to do would be to consider that perhaps that person has some information that you do not have, and that perhaps if you were to look at the very thing you disagree on from a different perspective, it may change how you see it.

I am not for the flat-earth theory, and I too would be completely open to engaging in a rational conversation with somebody who is for flat-earth, only because I may learn something I do not already know, and at the bare minimum, it will help me understand them better.