I feel like, if you think that so many people are missing an "obvious" point, then you must be the one not fully understanding something. The point you're missing is that "power corrupts" is not actually a compelling theme anymore, (it's been done to death fifty years ago), so if that really was the the point of season 8, that in and of itself is diappointing, and not an argument in season 8's favor.
The more compelling (and accurate IMO) saying is that "power reveals." It doesn't make you a bad person, so much as it shows who you'd be if there was truly nobody to stop you.
And the problem with that is, well, Daenerys has already had power for like five seasons now. Ever since season 3, we have gotten an in-depth look at what happens when you give Daenerys total control over a group of people. What happened when Daenersy had absolute power? She freed the slaves, and willingly chained up her dragons so as not to put any citizens in harms way. We've already seen what happens when you give Daenerys power, so this argument falls flat once you take that into consideration.
As for the rest of your comment: you seem to be mad at the author for... not going into extreme detail about every historical example they use? No, the american and french revolutions were not ~as simple~ as marginalized groups seeking retribution, but that certainly is in fact generally accurate. What exactly do you think started these revolutions if not marginalization?