Sharing your writing, especially creative writing, with other people and asking for comments is sort of like taking your clothes off and asking for a critique. There are probably some people for whom such activity sounds inviting, but most of us cringe at the thought.
Sharing with the Story Monkeys is possible for two reasons. First, like an evening of Strip Poker, everyone's got some skin in the game. Second, each of us gets in touch with his Inner Woman and we all nourish each other. Yep, I mean it. We go out of our way to remark on things we liked in each other's writing, we make our comments constructive (not "X doesn't work", but "I think X would work better if you did Y"), we help each other with ancillary writing tasks (query letters, agent contact lists, etc.) and even things unrelated to writing (reviewing resumes, IT questions, etc.). The Story Monkeys care about each other; we each succeed when we all succeed (hat tip: Glenn).