I believe the operational phrase is "If your shot is accurate"... In aperfect world, that would be right.
But, and I mean But, these aren't stationary 3d targets at known ranges. You aren't necessarily in a perfect stance. This is hunting not target archery. There are all kinds of opportunites for your shot not to be perfectly accurate. In that case, the extra width can really be an asset.
Sometimes the deer helps kills himself. A big, wide, broadhead lodged in a deer can do a lot of damage as it's jarred and jammed back and forth as the deer is running and the arrow is being slapped by branches. Bowhunting is an iffy sport to begin with, don't additionally handicap yourself.