One could imagine saying that if the function has a variadic last parameter, then we can match that to zero or more positional arguments after the last named argument. Not sure that that would be a good idea though, or how hard it'd be to implement. It'd be a pretty radical departure from the rules for non-variadic functions.
I too failed to realize that there was an implied, required, positional, parameter, of cardinality zero, following the named parameter. I see no reason to make that case work. I'm doubtful additional words in the documentation, examples or otherwise, would have helped people commit this edge case to memory. The error message would be of benefit but IMO it isn't worth the effort given the sparsity of complaints and the assumed rarity that all three of these dynamics come into play in order to have an obscure doesn't work scenario.
