Let's play a game: Save the Ancients!

[Lunaxia]

I would call ANY situation

And? My point is, why is the fact that it was a high-cost or bittersweet victory being used as a factor against them, when the same can easily be true for mortals for any of the crises they may face? As I said, they may weather Ancient-specific phenomenona, but so too do mortals have their own dangers that the Ancients would not be prone to that can easily result in a similar outcome.

And again, to bring back the original point: all of this was caused, by one man, by accident,

Aha, now let's be real, what happened was not by accident. Meteion returned with an answer he was not prepared for and she reacted unpredictably, threatening to go out of control, yes - because, as Emet-Selch remarked, his method was fundamentally flawed in a way he would not or could not hope to recognise because of his state of mind (however you might interpret it) and he chose to fly his little experiment under the radar to escape the review they might otherwise have had that might otherwise have prevented such an outcome. But the fact remains Hermes one hundred percent chose violence and permitted her to cause the chaos she did - had he not resisted, she likely would have been contained and at the very least caused considerably less damage than she did wind up doing, but he ultimately turned out to be another madman with his finger on the button and bears all responsibility for what ensued.

While those are hardly nothing, they are microscopic compared to the impact of Hermes' whoopsie. So yes, I think it's an absolutely fair argument to say that most of the Ancients were stupidly, absurdly powerful.

The average Ancient was creating blob monsters for the fascination of children on the street. Equating one genius rogue amidst millions over thousands of years tinkering with a force beyond his comprehension that few could ever hope to wield and unleashing hell - also known as another Tuesday in Eorzea - with the Ancients being dangerously powerful to the point they deserve to die is pretty yikes, to be honest. Do mortals deserve to be wiped out because of the likes of Xande? Zenos? Thordan? Nael? Amon? Pre-heel-face-turn-Gaius, with a rather sizeable "oopsie" of his own before we intervened? Ilberd? The mages of Mhach? Why is a bottom line of infallibility required for their survival, but not ours?

No, it was not a victory.

Zodiark was a temporary solution, yes - though the guy holding up for twelve thousand years makes me believe that he deserves a little more credit than he gets as a mitigation tactic at the very least, but let's say having him hold out indefinitely wasn't dealing directly with the problem - however, it's very hard to come up with a more permanent solution to an issue when the true cause behind your problems is withheld from you and your entire race is brutally murdered not long after.

I get the impression you're misunderstanding me

They remark on his creation abilities in the quests where you try to dig up the dirt on him in Elpis. I also think you're underestimating the connection between intelligence, knowledge and creativity and the power the Ancients had. Those factors are inextricably linked to the ability to create, which is the sole source of their power; not their ability to brute-force hit things super hard.

Again, you are misunderstanding me.

We don't actually know any of that, though. Hythlodaeus is worryingly down on himself in general, and as has already been said, he's comparing himself to the likes of Emet-Selch here - so-called one of the greatest mages the Ancients had ever known, and from there, it is safe to say, that has ever lived - on the basis of manipulating aether for transforming. We know he's been offered two of the highest positions in Ancient society; we know he is regularly sent for to consult on extremely sensitive matters seemingly beyond the likes even of Lahabrea to sort out, as seen in the Tales story; and we know he is capable in battle, but considers himself inferior to his fellows. We know nothing of his ability to create, the extent of his limits in combat, or really, anything else about him. Unfortunately.