Appa, it is good that the issue is raised now, instead of being raised at a later date. But I am not so sure about this.
Firstly, the contestant must know how to use the echo. The contestants mentor must know how to optimise the use of it.
If we are going to use technology to the benefit of the contestants, it has to be even and some contestants or mentors cannot suffer because of lack of knowledge on how to use it. The contest should not become one wherein talent has to bow down to technical knowledge.
Two, No doubt the Judges can make out good potential even when echo is used, but this gives scope for a discretion, which can lead to issues later.
Why not have one echo round, where someone who knows how to use echo and how to optimise ones voice posts something here, and all contestants get the benefit of it. And if one or two mentors have more knowledge about it, they could guide all those contestants who have doubts on it?
Alternatively, echo to be used in the final stages only, by which, we can all get some training in it, and all of us are on even platform without being at any disadvantage.