It's about time to add Coil story mode, isn't it ?

[Gardes]

Echo helps for dps checks. There is none left with current ilevel (or rather, there shouldn't remain any)

You would be surprised.

Echo won't help people for dives in T5 (misplaced, group in wall, end. Or too slow, people in wall, end. You can have 2 dead at a time but that's it.)
Echo won't help people for twisters.
Heck, some groups still fail at conflags...

It helps immensely with dives. People can get shot off the pit and run back in too late and get shot off again without dying. Add in a healer that can throw in small heals between that you're very likely to have the whole party survive when half the party gets hit by divebombs. Echo also help immensely with twisters. You can have people dying to twisters and you can raise them back up easily because the main tank can be left unattended for long enough just because of how tough he is now. People can die to conflags, especially when people push twintania hard enough (and not stop) that she flies up as a blue conflag is set down and the party can still make potshots at it and free the stunned person OR let the player die and raise them back up as snake spawns.

There are plenty of things in t9 that can cause wipes but echo can cut down on their occurence. Meteor can be cut down from 5 to 3. Parties can push phase 3 into phase 4 before 3rd heavensfall happens which simplifies the phase by a LOT. The bigger echo, the faster the group can finish t4, the less divebombs and elementals they will have to face, cutting down the margin of error. Tanks also become tougher and bahamut claw is less of a threat and less of a struggle for the healers to heal, even if you're one healer down.

People don't have to use echo just to pass dps check, they can use echo to push phases fast enough so there's less mechanics to deal with and less chances to fail. Just because some people can be amazing at causing wipes for the entire party does NOT mean echo does not help. Echo helps. It's not magic.