Not only is ODG right in the post you quoted.
But his plot devicey-ness goes much deeper than that.
As the universe's embodiment of Hope, he is the living plot device.
As such.
1 Superman can win, if he wills it so.
That's the thing about Superman.
In his universe, he beats all the guys the likes you have been discussing.
He beats the Tyrants, and Thanos' and Galactus' and Odin's in DC comics.
Any Superman fan can give a laundry list of demons and gods and galactic to universal level enemies Superman has beaten one way or another.
Yes. He loses way below this level at times to, but that's because he adjusts his power up and down consciously and unconsciously.
This is what the build up to Infinite Crisis, The event itself, and then 52 through Up Up and Away was all about. [Powering up to lead the way through Crisis. Then being a regular human after. Then summoning his power again as soon as he wanted it.]
It's also what Our Worlds at War build up and event and aftermath was about.
It's very literally written into those both of those stories.
The entire backbone of them in fact.
The backbone of most Superman stories.
Superman's power on an average day varies a lot because he's adjusting himself based on his encounters, and can be surprised.
But when he pushes himself, he blows the doors off.
More evidence is in the tussle with Black Adam. He started off by saying he doesn't have to hold back, and likened the blows to 'small bombs', and then started escalating himself more and more to the point his punches 'would have cracked the moon in half' when he chose to end it.
He was finding the level he needed to be at, no more or less.
And he does this on much larger scales.
And the only real catalyst to these ramps in power?
Choice.
Mood.
Himself.
[The story?]
This fluctuating difference in scope of power in a given story is why debating for or against Superman can be frustrating to those who aren't particularly built for it.
It's nigh-impossible to build an average out of this character, he is almost quite literally at whatever tier he chooses to be.
It's not even a case of 'high end feats', as he does this stuff year in and year out, issue to issue.