As an author, I take mild offense. XD
Just because a content creator only tells you about this portion of the world (let's say... a single continent), doesn't mean that 1. the content creator doesn't have other ideas about different land masses, 2. the world isn't full of other landmasses, as yet unbeknownst to the main cast, or 3. that another land mass (or planet) is bigger or smaller... just because someone who is not the content creator says or decides it is.
I keep my writing contained, often, to a single continent, or smaller. This doesn't mean I don't have other places in this world which I could talk about.
I often only mention one or two fantasy religions, if I'm discussing any of them at all, this doesn't mean that those are the only religions (or that their aren't cults and sects of those religions that worship differently).
I often only mention the races necessary to the story, though I have a veritable bestiary of creatures that do or could exist in that world.
Just because x is the only thing mentioned doesn't mean y doesn't exist.
[slayer-jinx-catface]
In other news: I can't believe I read the whole argument. The heck. I must be bored.