J-WO
Author of 'Pennyblade' and 'Feral Space'
Why not?
If someone can make and use a shield big enough and hard enough to soak up a phalanx surge, then an array of such shields could also be used by the phalanx to bounce off any little shower of puny javelins.
Phalanx shields were comparatively small and would have to be lifted to block most javelins. Lifting a shield over your head in a phalanx was difficult and would help to disrupt the phalanx itself- just what the Romans wanted. Plus the Roman javelin--the pilum--was designed to hit shields and then buckle-- breaking up the phalanx formation and negating the shields.
Someone using a short sword to cut down spear heads would have to be moving really fast, at top speed really, for the duration of the battle, which could last from morn till dusk, if he's to avoid getting a spear in his throat, face or gut, while he's busy lopping off spear heads. Now, only a Hercules or an Achilles could do that sort of stuff.
Yep, they call it professional training. And using a body shield. And using the enemies growing lack of cohesion.