Yes, it does. And to be clear, I'm not saying that sanctions were ineffective in this case: as you say, they'd be much more effective against a nation like Iran

Yes, it does. And to be clear, I'm not saying that sanctions were ineffective in this case: as you say, they'd be much more effective against a nation like Iran with a relatively open economy and society. However, that same factor makes most other nations much less eager to keep the sanctions, because they're losing the money they could make by trading with such a nation. So at the first chance to make a fig-leaf deal and abandon the sanctions, of course they jumped on it.