But you can check the number of arguments without resorting to prototypes. In my opinion, it's far easier to check the length of @_ than to use a prototype.

As I said before, the problem is that prototypes don't just check the number of arguments. They can also make subtle changes to the types of arguments (as seen in the original post in this discussion). And I think that in many cases that makes them dangerous and best avoided.

Tom Christiansen once explained the problems, so I don't need to go into detail.