What would you replace Rescue with?

[Gemina]

People did EX- / Savage-fights in FFXIV long before roleskills including Rescue existed, so why do some healers insist on the move as if it was their only purpose?

It's not like you can always perfectly match your timing with the server-tick, anyways, so players will still continue to fall down at our sparkling example of Titan or get killed by AOEs / mechanics.
->There are even those who return to the danger-zone because they don't understand your motivation to pull them around, so it would be more effective to say early in chat things like "Stay in green soup or Vorgal's Megadeath kills you." and so on to prevent K.O.s or even wipes.

That is totally understandable, but not a reason to delete or not make use of the skill today. We've also completed content without Seraph, Earthly Star, Misery, etc. Healers like me insist and support rescue because the current state of healers leaves us with very little to keep us engaged in combat out single target spam and whack-a-mole healing.

Pre pull tactics is all well and good, and I highly recommend groups do this. Sometimes, instructions are not followed though, or if a player is new to the fight they may not get placement down on the first try, or make an error (we are human after all). Rescue is a tool that can be used to quickly communicate to a player where to stand because chat is no longer a luxury, or even a tool that can be used to get through mechanics during combat.

Is it needed? No. It is useful? Yes.