There is no doubt that form is more important here, as long as the arrow is flying "decent" at first.
However the reason for so many tuning subjects is because that is the easiest thing to fix.
Say 50% of your accuracy / consistency is form related, and 50% is tuning the arrow. With a little money, a couple posts for suggestions on where to start on Tradgang, and half of a day - you can have peprfectly tuned arrows to your bow. Now you are 50% there.
Now the work begins, and this is where the majority fall short. Fixing the other half of the equation takes long hours, practice sessions, patience, days of frustration, etc..etc..etc..
But I will add, For those who have the tough part done... the form down perfect, but haven't put mych thought into the tuning side of things because good form is allowing a "good enough" arrow to fly out of the bow, I challenge you try to tune a "perfect" arrow.
Its truly amazing how much more forgiving your shot becomes.
Plus, you've already done the hard part! Why not go the rest of the way, right?!