Because there were no offenders. DTCC raising collateral requirements on an ultravoltile stock with a high chance of price collapse is just... a reasonable thing to do?
Do they have a prepublished volatility-collateral chart that applies for this and all similar scenarios or was this an adhoc rule change made arbitrarily this one time? Can you show another volatile time where similar action was taken?
Can you point to a GME like price action of a non-penny stock ticker? Of course we both know the answer is no. Things shot up, things shot down, of course people who bought the hype lost money. There is nothing surprising here.
Evidently you don't know what you're talking about - of course I can. $VW 2008, $ACB 2019, $TLRY 2018 to name a few. There is much more, simply go through tickers on D1 chart and you'll see.
Then why disable buying and not selling, if things were volatile the exchange could have stepped in and stop the trading. There was really no reason for DTCC to increase the margin to 100%.