This is exactly backwards to my eyes. Perl's autovivification behavior (assigning through a empty reference to something autocreates the object of the right type) makes nested data much, much cleaner.

Who hasn't made some weird dictionary with its values being lists and forgotten to check for and write code to create it when it doesn't exist, and had to fix that later after a runtime crash? In perl that's literally covered by the one-line assignment you used to set the field you parsed.

This is why it's sad that everyone's forgotten perl.