CCing mobs before they're aggro'd !== saving the group. CCing mobs before they're aggro'd == you'd better reapply the CC once the duration runs out if the current group isn't dead, otherwise every one of those mobs is going to go straight for the person who hit them with the CC.
CC !== tank defensive cooldowns. This is a thread about tanks using their defensive cooldowns, and discussing whether or not a DPS or healer's CC is worth using is entirely separate to that discussion. You also seem to be veering towards a false perception of me or really anyone who disagrees with you as an elitist (which is ad hominem and invective - see my signature). All this is to say we are very far off topic, and the discussion at hand is not going to do very much to help tanks at all.
General statement of reality !== lie. You may have circumstantial evidence of BLMs saving groups, or your own knockbacks as a WHM (which, let me tell you, can get REALLY annoying for a tank if they're not communicated), but most content runs I've seen in this game should not require it. Interrupts are one thing, but there are very few points where abilities must be interrupted to avoid a wipe. If a group is going to wipe, and there are DoTs out, AoE sleeping is only going to buy you maybe 3 seconds. Its usefulness is extremely situational, and in any DF setting, you're much more likely to see value from killing stuff more and having a tank who knows how to handle their cooldowns and group enmity than you are from CC.
Good on you and your friend, though.