That's... not actually how give sauron the death star is supposed to work. it's how a lot of authors who don't know what they are doing use it, but not what it actually means.
What it means, is that if you give a character a massive power boost as part of the stories premise, then you should also increase the power level of his opposition, because otherwise they the character won't have any challenges and it turns into a curbstomp-fic.
and what idiot thought that scaling the antagonists power with the MC's after story start was a good idea?! I want to give them a review saying they're doing it wrong! yes, villains should be allowed the chance to grow and escalate, that does not mean that increasing the MC's power directly makes the villain stronger like some demented realtime port of TES 4.
as for the thing about harry potter fics? yeah, they're really screwing it up. you can't give the MC enough power to stomp the only villain in the setting from the get go, and then try to fix your shit with an idiot ball and a Diabolis-Ex-Mechina. that's shitty writing.
And you know what the sad part is?
Almost every single Harry Potter fanfic I've seen still brute-forces the Resurrection, and vast majority of them also pull some bullshit like 'Well, the prophecy says they have to be equal, so I have to boost Voldemort!', conveniently ignoring the fact that Voldemort was superior in almost every single way to Harry in canon, and Potter didn't get any sudden Shounen-style power-ups from that fact.
Either that, or they go for the 'Well, Voldemort used Harry's blood to resurrect himself, so he got some(most?) of Potter's power, too!'.
Even when they previously mentioned that the pure-blood doctrine is bullshit, and magic is does not lie solely in blood.
They do things like that even when they had the main character imprison/kill every single person who could've aided Voldemort in his attempts to return, but conveniently spared a single random death eater who didn't even know Riddle wasn't completely dead, but who ended up bringing him back.
It's so... forced.
You see, it's not the part about villains not being strong enough to challenge the protagonist that I find problematic.
We've only seen Great Britain in the Harry Potter series, as well as some very scarce mentions of other places.
The world is a huge place, and there are bound to be other psychopaths trying to carve their way through the world. Even if none of them are powerful enough to be troublesome, you can always turn the story into a crossover at some point and throw an OCP villain into the mix.
Or just have the main character screw up with magic and fall into a world they know nothing about, but which has a lot of powerful foes to fight.
Voldemort is not the only bad guy to have ever existed. You can always make more of those.
If you can't find a way to make the story interesting without having the
hero-is-weak-but-grows-stronger-and-overcomes-trials-with-blood-and-sweat stuff, then at least don't FORCE the same damn villain into a position of power through a Diabolus ex Machina.
If you made your character strong enough to curbstomp the villain, then let him do so, write some reactions to that and then throw some other bad guy at him, instead of having the supposedly-curbstomped bad guy come back to life
STRONGER THEN EVAR.
That is what annoys me so much about it, and what turned me off from most Marvel comics.
There is only so many times I can see Joker come back to life before my SOD shatters like glass.
Not only do many authors completely misinterpret the 'rule', but they also don't bother to do it in imaginative ways, and just pull out the same guy over and over again, boosting his power constantly in the most convoluted of ways.