If I understand what you're saying, you provided a reason why variant arguments should not look like function application (because they have different semantics than function application), and then in the same paragraph suggested that variant arguments should have tuple syntax, while admitting that they don't actually have tuple semantics either.
The truth is that variant arguments in `Reason` actually do not have function application syntax - note the distinguishing, leading capitalized letter on the variant. Sure, they share the fact that arguments are specified via a space separated list, but function application doesn't have a monopoly on the syntactic pattern of things separated by spaces. The argument quickly breaks down.