Variadics are a prerequisite for this sort of introspection, not an alternative. The design you linked uses an ad-hoc keyword to hack around their lack.
I agree, but I think there's a possibility of keeping the variadicity only as introspection "compiler magic" and coming up with a higher level implementation of variadics for the general language that drops naturally out of introspection. My hope is that eventually variadicity will just be "only library code" that you can just inspect how it is implemented via introspection.
