The reason I think T5 is hard for a lot of people...

The echo doesn't save you from one shot mechanics that doesn't rely on your HP or a dps check. There are a few things in T5 that one shot you simply because you or your party didn't handle properly.

Getting dive bombed into a wall
hit by twisters
hit by the dread knight if it's not killed fast enough or standing too close to it
the eggs if there is not a tank soaking them in the neural link or not running to a neural link if one is loose
tanks and healers not ready for death sentence
not moving from liquid hells in the last phase
her two hour after snakes wether by standing too close to the little ones when they die or not standing in the neural link.....

There are a lot of mechanics that have to be handled properly. The echo can't do shit for some of that.