That's true, but it's easy to misrepresent if you don't include another important insight:
"I believe you find life such a problem because you think there are the good people and the bad people. You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides." -- Lord Vetinari (by way of Terry Pratchett)
Really? I call. There has to at least be a shade even though I think he was incorrect.
Because otherwise all bosses would be equally shitty and you would not be able to foresee with uttermost certainty how bad people will become shitty bosses when promoted to power.
It is equally obvious in the military how you know who will turn out to be really bad people once promoted to sergeants.
The upshot is that "Okay, we just need to find someone who power will reveal is not shitty." does not and cannot work in the general case (of amounts of power sufficently large to be worth abusing - your 'good' sergeants are still sergeants, not generals or absolute autocrats).
I believe Robert Caro was more insightful than Lord Acton:
Power doesn't corrupt; it reveals.