Can no longer reveal stealthed units with their respective abilities but 
and most likely a few others I can't think of still can. Lee Sin's makes sense thematically, but why take the rest of them away if you're not going to take all of them away?
Zair Umbras1 votesSame reason why Fizz's Q became 'dodgeable' when they removed J4's ulti 'dodgeability'. You know, when you flash out of the animation, it didn't do damage, now J4's always does damage and Fizz's won't do damage if you flash out of it.
The Bearded Bard1 votes[{quoted}](name=Zair Umbras,realm=NA,application-id=3ErqAdtq,discussion-id=PFZzZiJN,comment-id=0000,timestamp=2015-04-12T17:53:16.889+0000)
Same reason why Fizz's Q became 'dodgeable' when they removed J4's ulti 'dodgeability'. You know, when you flash out of the animation, it didn't do damage, now J4's always does damage and Fizz's won't do damage if you flash out of it.
That has absolutely nothing to do with what the OP is about. And for the record, Poppy's E is also dodgeable by using any type of dash when she uses it. Damage and all, not just the knockback.
Zair Umbras1 votesHe asked why other champions can't do X because others do X. I gave an example of the same principle in use. Those champions can't reveal stealth anymore, but the others can. Fizz can't hit a target who flashes anymore, but J4 can.