Why $releases[ $index ]->{'versions'} is an array reference wrapper around the hash reference, not just straight hash reference?

#  Why this ...
my @releases = (
  { ...
    versions => [{ version => $stable,
                  files   => [ "foo-$stable-1.i386.rpm"]
                }]
  }

#  ... not this?
my @releases = (
  { ...
    versions => { version => $stable,
                  files   => [ "foo-$stable-1.i386.rpm"]
                }
  }
);
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