restricting the scope of this makes sense.

also: just because an argument is listed in the docs with a name does not mean that that name is the most appropriate; part of adding keyword support should be choosing a sensible name.  Keyword arguments, when used, should increase the readability of code rather than add to confusion.

I intend to bring this up for a brief discussion at the language summit next week as representatives of all the Python VMs will be in the same room at once.  Goal: define the appropriate scope or at the very least non-scope.

As for performance and memory use, yes, it could have a small impact but it should not be large [worth measuring] and that seems like something we should fix in a more general way rather than by limiting the way methods can be called based on how a given VM is implemented.