I briefly read an article a while ago that spoke about how the RF have done an exceptional job with Kate, a good job eventually with Sophie and an awful job with Diana, and Meghan was going down the route of awful for how they handled her. But it ultimately was down to Kate and eventually Sophie realising they worked for the firm and they're not bigger than it, just like Philip realised, but Diana always liked the celebrity and fame too much that she eventually worked for herself. A bit like Harry and Meghan now, they loved the celebrity friends and fan base.
People can say Meghan has too much of a voice to have to give it up or Kate is a pushover, but I've always seen it more as Kate realises how good she has it, she loves in a palace, works a couple of days a week, travels the world and wears fancy dresses, boo bloody hoo if the press are sometimes mean. There's a reason royals don't leave, because the grass is unlikely greener.