Well, believe what you want, but after I got more than two weapons I started to use the chainsaw strategically, as I described it in my post. Of course, gimmick gameplay is kind of retarded, but that's how they chose to roll.
I mean, if you just left it at "overstating" then that's one thing, but you said you rarely used the chainsaw for ammo. On nightmare. I just can't buy that in a million years, sorry. Maybe it felt like rarely? I dunno. I will agree that the further you get in the game, with all the upgrades and guns, the less you have to do it.