Afaik, only those who heavily exploited was banned. Not sure permaban or 72hr ban. Krippirian was unlucky, I guess someone at anet didn't like him, and permabanned him for "advertising" the exploit. But he has since been unbanned it seems.
Blizzard as in WoW? Well the difference between gw2 and wow is that there is no subscription, permaban for heavy exploiters = high chance of selling another copy of the game with no lost in subscription fee while preventing a ruined economy. Look at Kripparian, he did buy a new account lol. Same deal with the karma weapon exploit, only those who heavily exploited it by buying hundreds were banned. I know this coz I bought 5 for my own use and had no problems so far.
Can't say they are entirely stupid for banning people, coz it seems like only heavy exploiters were banned. But if they start banning light or accidental exploiters, then we have a problem.