It is an autovivification problem, yes. However, the autovivification occurs due to the aliasing of grep (and map and sort and a few others). That's why aliasing is correctly the focus of this meditation.
In general, if you think something isn't in Perl, try it out, because it usually is. :-)
"What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against?"