No, even then there are things like Mandatory Integrity Control and Windows Message Restrictions / UIAccess. I'd dive into to deeper but I just got home from going out haha. Those terms should help you dig into it though!
I do fully agree that desktop OSes are a legacy security model and they can't hold a candle to that of iOS. Android is getting there, but because it also started from mostly an open all-access model it's been having the same warts.