There's no sarcasm. What I said should be interpreted literally.

$_[0] is not created

It didn't exist before splice(@_, 0, 0, 1) and your equivalent, and it does afterwards. That's the very definition of created.

(If you're gonna argue that $_[0] did exist, then its $_[$#_] you created.)

Where splice and my create the variable differs, but both create a new scalar variable.

The rules say "no extra vars",

Again, you've created a whole bunch of vars. If you're not subject to your rule, I'm definitely not.