Larry, ISTM that you are bulldozing your way through something that isn't an actual problem to be solved.

>  I can see why you'd think this was a waste of time.

I don't think it is just a waste of time;  I think it is a bad idea.  You have a very strong notion of how function signatures should look (i.e. the number of arguments being irrelevant) and you want to impose your ideas on existing, stable APIs for zero benefit.   

> I view giving all builtins in Python valid signatures
> as a worthwhile goal unto itself.

I can already model the behavior of repeat() using *args and **kwds, just like I can for int(), list.pop(), range(), and slice().

You don't seem to get that those tools already work, that people understand them, that they've been stable for a long time, and that they don't need to change for any reason other than that you've worked yourself into a snit about it.