Villain, being the light 3bettor in position, might have for example A5s or 56s in his range, whereas we can't really have a piece of that flop at all apart from a few combos of flush draws, and our overpairs are largely capped at QQ or so. What I'm saying is, since our value range is so weak here but villain has many bluffs in his range, why are we ruining a perfectly fine bluff catcher?