I think there's a very big spectrum of people between 'never moved out, mummy still does their washing, wouldn't know where to start setting up their own utility bills' and 'moved home after a life event like a relationship ending or a job change because it's financially impossible to live alone in their area'.
People who've never moved out by their thirties, yeah, I do wonder if they're going to feel the lack of life exprience when they finally end up house sharing or cohabiting with someone else - there's a lot you learn living 'on your own' and you become a lot more self-sufficient.
Those who've moved home for other reasons - well, they've usually learned those lessons already and are more capable generally.
It's the people whose parents still do everything for them, don't make them contribute financially, etc I do raise an eyebrow at - my sister was one of them and is finding the most basic 'sharing a house with someone' compromises and financial requirements absolutely intolerable now because she's never learned how to be an adult.
So really it's not about where they live, it's how they behave, whether they were living at home or not - if they are coddled adult-children who can't do anything for themselves then yes, I judge. Otherwise, no: life's expensive.