I don't think you or the replies to your comment are addressing the parent point. It's not a game where something is "allowed" or not. They are saying that they

I don't think you or the replies to your comment are addressing the parent point. It's not a game where something is "allowed" or not. They are saying that they suspect most people would not be able to themselves demonstrate that the earth is round, and that their argumentation would end up relying on faith. Whether such reliance is "allowed" is irrelevant (This made me think of a kind of inverse example that came up recently: I had made a point in an online discussion and offered an argument for it in my comment. Someone replied and said they looked up what I was talking about and didn't see anything about what I'd mentioned, and so didn't accept it. The disagreement was not about the merits of the argument, but that they couldn't find that argument anywhere, and so apparently instead of considering it, they just rejected it as invalid. I've seen more variations of that recently, the whole "citation needed" thing, where people think that an "authority" is automatically necessary vs just thinking about what they were told and deciding if it does or doesn't make sense)