ANY infantry - or for that matter cavalry - that get "crushed" too closely together (ie. to the point where they can no longer wield their weapons effectively) become little more than sitting ducks, irrespective of who exactly does the pressing and what against. Heavier equipement just makes them more troublesome and difficult to kill, whereas lightly armed men can be massacred with relative ease - no need to hack and stab through body armour, no ?