Originally Posted by Dorkus Malorkus
Because it's a completely dry flop that SB has a close to zero chance of having hit while also being OOP. Unless we're lucky enough to catch him with the one remaining Ace, he's going to invariably fold whereas if we let him see a turn (a) he could pick up a draw or make a second best hand that we can get value from, or (b) he could bluff at it because we seem weak. There is no reason to bet the flop unless you have a read on SB as being incredibly drunk or something.
There's also the argument that the majority of a flatting range from the blinds vs EP is (or "should" be) pairs. Pairs that flat the flop often once, and unfortunately fold turn, but when we check back, often fold to a delayed cbet on bad turn cards.
For the most part though we do have the deck crippled, and there's also the argument that those pairs that might flat the flop could bluff the turn and/or river, but I tend to think that most taggy micro players just try to call flop or even turn and get to showdown rather than turn their hands into a bluff on turn/river.
I think as a generalization, the taggier the player, the more we should be cbetting here, and the looser the player, the more we should check back since they have so many more SCs/random unpaired cards that can turn lots of draws and pairs and 'hit' the flop a lot less.