Yeah, that's how it is now, I know.

I'm saying if they went full on with it (which would be fun and daring), SGE potentially could screw itself by not saving up for the phase, whereas other healers continue to build those resources because Aetherflow, Lilies and, uhm, generic cooldowns, are all based on time. The same timeline they devise the encounter around.

Also, it would mean SGE gets screwed even more if it died than just low MP and weaker heals, like current and StB SMN, DRG, RPR etc.

These aren't impossible challenges, like you said they could just save up whatever they built, but man does that sound like balancing that would be a bit more work and SGE might potentially be better or worse than other healers in some cases by a statistically significant margin...

"Let's just play it safe and limit their healing via damage to a weak Faerie Regen," -the senior job designer in response to the OP's fun suggestion