I find that forum posts (like on Hacker News) help a lot with writing essays, if for no other reason than it helps you develop your arguments. Ditto blog articles, though every blog is different and most of the "good" blogs are terrible.
Stories are different, though learning to construct an argument helps you plan out stories. Learning the aesthetics of a language isn't something forumming helps with. And poetry is an entirely different entity from either: it's almost all aesthetic.
The problem with feedback is that each thing you do is trying to do something different. If you state yourself clearly online, there's not much more you have to do. And yet look at somebody like why the lucky stiff, who's elevated his writing style to a level above anything I've encountered online. He doesn't have to do that, but he does it anyway.
Stories are different, though learning to construct an argument helps you plan out stories. Learning the aesthetics of a language isn't something forumming helps with. And poetry is an entirely different entity from either: it's almost all aesthetic.
The problem with feedback is that each thing you do is trying to do something different. If you state yourself clearly online, there's not much more you have to do. And yet look at somebody like why the lucky stiff, who's elevated his writing style to a level above anything I've encountered online. He doesn't have to do that, but he does it anyway.