The mixup in 21122, at least before the string is performed to completion, is not in what EB will cancel into, but in when he will cancel. If he cancels at any time before the final 2, a jump over punch nets you a full combo punish on both tackle and ex grenade. You are only forced to make a read between throw and grenade after that final hit due to 21122xxex grenade being a true blockstring. If you read the throw you get a full combo punish, if you read grenade you get out of pressure and EB loses a bar.
Of course, 21122 is huge, and we definitely could have gotten hit harder, but I feel that string combined with the oki from tackle and ex grenade was what set the character apart, that was his main dirt. If you compare similar characters, they all have 50/50s, but they have something else as well, be it a vortex, restand with huge advantage, setups, better frame data, etc. etc. - those characters get those extra things, the things that make them unique, while still retaining decent damage and wakeup pressure. 2/3 variations now have to sacrifice a lot of damage and corner carry in order to keep wakeup pressure, and its not like gunslinger or marksman were on the higher end of the meterless and metered damage spectrum to begin with.
At least when you guess right against 21122 you get a full combo punish. Guess right against summoner quan, and he's still +.