Largely this is a class thing - writers tend to be cosseted little middle-class kiddies who think that the world owes them a royalty cheque. But just doing it - being in your room for years on end locked in your head alone with invented ghosts - it weakens and softens the body. And I know I can't just live in my head.
And of course Marc Cherry heightens it and makes it hilarious. But there's so many universal themes in the show and he made it so funny. We knew he was onto something if he could keep it up and thankfully he did.