At its heart, writing is an act of communication. At some point a writer has to turn his/her work over to someone else to read. Otherwise, they will never learn if they have been successful in conveying their ideas onto paper/into pixels.
My initial drafts tend to get sent out to a very small number trusted of beta readers. I need to know if the story works, if the characters work, if the funny bits are really funny, and/or where the holes are that I've missed. With the latest draft (a major revision that my agent requested) I widened my circle of beta readers to include several people who had never read the manuscript before. I not only wanted some fresh perspectives, but I wanted to gauge new reactions against older reactions.
What might work for one person might not work for another; what one person doesn't like isn't seen as anything troubling by another (even after specifically asking them about the point).
Through all of this community involvement the author needs to hold comments up to his/her own standards of what holds true for him/her with the story and characters. The balancing act, though, is between rejecting a comment because 'that's not what that character would do' and needing to better explain the character's motivations so the reader understands what the character might or might not do.
Each one of my beta readers offered me an insight into the story that I didn't have before. I made changes based on their comments that I know made my story much better, much stronger.
Getting the comments needed to carry out a good revision can be a community event. Putting them to proper use, however, is still an individual act.
My thanks to all of my friends at The Writer's Loft, MA who helped with this revision!