Here's my take. In real life, when tyrants are violently overthrown, the results are usually less than pretty. Granted, most dictators aren't going to peacefully back down like here, but this show has always been really optimistic about that sort of thing and did present a somewhat realistic possibility. Lots of the worst people in human history aren't complete sociopaths and genuinely think that what they're doing is right. When the worldview they have and the world they've created goes against them, causes them unspeakable pain, anguish, and grief, their empire begins crumbling and family turns against them, who's to say they wouldn't change their tone?
We see this very clearly with Yellow and Blue, but it's a bit more subtle with White however. Notice how when Yellow and Blue start talking, she doesn't mind control them or cut them off in any way. She very easily could've at any time, but she doesn't. It's because she's going through a crisis. And likely has been for awhile. White thought of herself as perfect, as God, more or less. She could do no wrong. And then the rebellion happens. 'Aw well, Pink's just playing a game. She'll come around and and we'll put this behind us. She has a history of this kind of thing after all, it's why I took her pearl.' Only it doesn't go that way. Resources are lost, morale plummets, the diamonds she created to reflect her inherent perfection are going through an emotional crisis. For once, reality has slapped her across the face and showed that she and her empire aren't nearly as perfect as she so childishly pretends. So she hides from it all. Up in her tower, it's easy to think that everything is fine, why no she's not sad, that's just Blue again. Silly Blue. Everything is perfect, Yellow and Blue can practically run things themselves! They can't, of course, especially not now, but try telling her that.
Steven's arrival even plays into this initially. It wasn't a problem! It was just a game! Everything is back to normal. But then it wasn't. And here her two other diamonds are telling her that she messed up. Notice that she doesn't blast them immediately. She stays silent. Suffering in silence just like everyone around her in an attempt to appease her own ego. So she doubles down. It's all Pink's fault, she needs to justify herself by surrounding herself with lower lifeforms, nevermind that White did the exact same thing. She's trying to justify her worldview with everything she has left in her system, with every excuse she can think of. She doesn't ruin things, she fixes! Look at how much happier the Crystal Gems are now, under her control! The rest is self evident, Steven undermines both her world view and her understanding of the situation, causing her to throw a tantrum. Steven calls her out and White fells something she hadn't felt sense she created Pink, revealing that her attempt to perfect herself by giving her flaws to her fellow diamonds abd dividing bits of her personality all across gem kind didn't work. And it's the staw that breaks the camel's back. If a real life equivalent happened to someone IRL, who's to say they wouldn't change too?
Now, I'm not saying the diamonds are off the hook now. They aren't. At all. And that's why Season 6 exists. They're still plenty of things that need to be addressed, just be patient. My hopes are high, but we'll likely have to wait another hundred years too see if I'm right.
