Steven Universe - Yellow Diamond's Perspective

That might actually be likely. Sure, we don't know a lot of the Diamonds yet, but what little we have points to this more than anything else. That the Diamonds might have been close to one another.

Blue Diamond was helping against the rebellion, and I assume that was before Pink was shattered. And Earth was Pink's responsibility, meaning Yellow's obvious resentment towards what happened seems more personal rather than "those Crystal fucks made me look bad."

That said, if it was like that, I'll question why the Diamonds haven't already sent their entire army to glass the planet from orbit yet.

Well, the Cluster Project is likely one thing. Another is that the corruption 'bomb' as its been referred to is muuuch much worse. "This is life for you now! End! Less! Suffering!"