Curtain Call isn't a soft or any other form of enrage though? It's like saying E7S Tornado or A12S Fountains are some form enrage, they clearly aren't. It's just a mechanic that happens to dish out a lot of damage and falls where groups typically clear the fight. It doesn't ramp up, it doesn't eventually wipe the group, it's just another phase with the actual hard enrage coming as a distinct aoe a good amount of time after curtain call is resolved.
FFXIV has startlingly few legitimate soft enrages come to think of it. Even JKicks style AoEs towards the end of fights don't really count as they are always just a fixed sequence of AoEs before the real enrage comes. It's a healer check you can skip if your DPS is good enough for sure, but it's no enrage. I wouldn't even call ThordanEX's final couple of phases a soft enrage even though I don't think I ever saw a pug beat them if they got there
TitanHM's stomps are close but no cigar as I'm pretty sure they are capped at some number, ShivaEX and her damage up stacks is probably the closest but even she never simply does so much damage that it becomes unsurvivable, she simply does yet another hard enrage once the sequence has looped enough times.
As for suggesting that nothing really changes during the mechanic. That's selling things a bit short no? You've cleared it right?
When nuking, you mash the button too fast nothing changes, you mash it too slow your logs go down but little to nothing else changes in the majority of content.
When healing curtain call, you mash the button too fast you run oom before the clear, you mash too slow, people die, tethers pop and the raid explodes. Range is also a major concern.
Healing Curtain Call (or Act4 to a lesser extent) is most certainly not the same as smashing glare.