I think it’s more of a personal thing than saying it to someone according to the post. What I mean is I think the post means don’t disregard something before trying it at least once because if you don’t you can’t really understand how it would go. You might have a feeling but until you do you can neither confirm or deny it. I don’t think it’s about telling someone else to not knock it till they try it but telling your own self to be more open
just don't.