I hate this argument, not because it isn't correct as far as it goes, but because it's very often represented as much more broad than it really is.

That is, yes, we can be reasonably sure that time travel mechanisms whereby tourists definitely could and would become known in our time period will not exist (even this isn't the same as can't exist). But this is a very small sampling of time travel scenarios you could imagine, and I think it's far from the only thing described 'classically' by science fiction.