Ghishlain already pointed out that you can still overheal and achieve lilies. You can heal a tank at 50,000 HP up to 55,000 HP with a 10,000 heal, generate a lily, and still overheal by 5,000. The only overheal it doesn’t show is when the overheal is 100%; that doesn’t mean that it doesn’t still proc at a 50% overheal, or even a 99% overheal.
DPS jobs rely on their gauge to actually function in their Stormblood incarnations. WHM does not. Most jobs could have continued to ignore the gauge if things were left on the status bar (Greased Lightning stacks, Blood the Dragon timer, Aethertrail/Dreadwyrm, to name a few), but aspects of their core performance has been made reliant on the Gauge. WHM has no such issue—you could hide the gauge away in some obscure part of your HUD, cover it up with a sticky note on your screen, and play WHM exactly the same without referring back to it with absolutely no detriment. That makes the gauge (and the lily system since it’s the only thing the gauge is used for) worthless.
There is a huge difference between saying that you can ignore DPS gauges and you can ignore the WHM gauge. Ignoring the DPS gauges actually detrimentally affects your performance; ignoring the WHM gauge does nothing. Nothing changes with the way the job plays, or your performance.
You really, really confuse me, because in one breath you say that there is nothing wrong with the lilies, and then in the next breath, it’s that the lilies are useless. And then you seem to be continuing to defend the purpose of a poorly implemented system. There is something wrong with the lilies if they are absolutely worthless to the core gameplay of the job.