What's not under question here is the US response to a threat, nor its tactics, which were necessary simply because the F4F was outclassed by the A6M. In hands of powers with less training and resources than the US Navy the differences between the two types would have been more marked. To be fair, the standard of aircraft carrier based fighters between 1940 and 1943 up to when the F6F enters the scene isn't that spectacular, there's the A6M, the F4F, the Brewster Buffalo, the Fairey Fulmar, the Hawker Sea Hurricane, the Gloster Sea Gladiator the Supermarine Seafire I (later Seafires were obviously far more potent), so the A6M looks pretty good compared to its contemporaries.
To really appreciate the capabilities of a weapon it needs to be considered next to the other aircraft in use at the time it was, rather than attempting to compare it to everything else. Obviously the A6M was in service until the very end of the war, so that means it was contemporary to almost every fighter in theatre throughout the war, but to begin with, in the first year when the USA is taking its first steps into the war, the A6M is by far one of the best fighters in theatre.