>>it seems that not all hooks should have @args, but rather something else.<<

Thats what I first though but Alex explained that some hooks have multiple arguments so using:

my @args = @_;

....covers them all whereas:

my $hashref = shift;

....may be skipping the 2nd arg onwards.

You can still obviously access the hashref using the first method with:

%{$args[0]}

...or for specific keys:

$args[0]->{key}