Array Vararg Template Paremeters

[Q. Schroll via Digitalmars-d-learn]

For a function, one can have a vararg parameter at the end like 
this:
int sum(int[] ar ...) { /* code */ }
But for templates, such a declaration is an error. Is there a 
specific reason why?
I know I can do it and ensure all the template parameters are 
values and are convertible to the desired type. However, it's 
easier to just use an array.