Change Your Mind

White Diamonds can't control too many gems or she risks over exerting herself.

White diamond telling Steven he's "acting like a child" doesn't make sense because not only do gems not age, but white had also never been to earth before that episode, so she simply could not have known what a child was, let alone how they behaved.

Though in the epilogue series Steven Universe Future, it's shown White's powers can work in reverse. She likely unconsciously picked up the knowledge of human aging and maturity form Garnet, Pearl and Amethyst; they watched a lot of children grow up ever since Greg met Rose.

Featured in MsMojo: Top 10 Most Heartbreaking Cartoon Series Finales (2020)