map { ++$_ } [1,2,3]

should throw an error, because the mutation of a reference itself doesn't make any sense.

And I was asking if there is a reason why they don't.

The whole discussion about "literals" is unfortunately only distracting,

(though Wikipedia is on my side: Literal (computer programming): "a notation for representing a fixed value in source code" but I don't wanna continue this.

NB: fixed doesn't mean (compile-time) constant. It means not variable)