And here's why....
First, it magically sucks away time. Yes you can follow agents, editors, writers, hashtags, blogs, and network out the wazoo - but when its all said and done, you'll find that an hour went by...an hour that could have been spent writing and making progress on the skill you're trying to develop.
Second, it's a way to get the "real truth" in blog form. I follow a several writers and a few of them use twitter to filter out the best of the best blog posts on writing. Many of them are very helpful whether it be plot development, showing not telling, characterizations, how to query, how to synopsize, etc etc. Others, however, give you other ideas such as how poorly writers are paid, how complicated it is to get in the business, how bleak the market is looking, or how trends are dying and if you are writing within that trend that you are basically screwed before you even start. It is these posts that mess with your head, tell you to stop trying and that you are wasting your time even making an attempt.
Third, those agents and editors that you follow are way too honest. Yes, they are wonderful for quick networking or asking questions, learning about the biz and I know of one person who got her agent strictly through these 140 character twitter conversations. But there are the others who poke fun at Queries that are submitted, that complain that they see the same thing all day long. I totally understand that. It's their job. but for writers trying to learn, it sends yet another message that unless we come up with the most original idea ever, we don't have a shot. And I hate to say it, but there are no original ideas anymore.
So...that being said, would I shut my Twitter/social network down...absolutely not. Because here's the thing. You can overcome the time-sucking/hour-wasting moments by setting parameters. You can choose to ignore those blog posts that are disheartening and blatantly obvious. You can unfollow those agents that give the hard truth. Or you can continue to do all three and say "Screw it" because in the end, if you're writing for a market, then you will NEVER sell a book. A story has to come from your heart, not your business plan. If you don't believe in your story 110%, then no one else will either.
My choice is clear. I'll keep reading those posts, keep following those pessimistic agents and their #queries hashtags and then I'll say what my Daddy always says to me when I hit a rough spot..."Keep plugging along, kid"... because in the end, my story is mine and even if an agent doesn't love it, I can still share it with whomever I choose.
...that is, once I get my tail off twitter and finish writing it! :)