Well, for the record I have been posting 99% of what has come out of my pencil since I started drawing again. I see my online sketchbook as a record of what I am doing/have done, not as a portfolio to showcase my best. You have to start somewhere, and it is liberating to post what you might not be proud of. There's much to be said about getting over yourself and your pride.
edit: What really confuses me is when people decide they suck at something and then they run off and sulk and feel terrible about themselves. If you were a mathematician and were having trouble with (insert math difficulty here), you would go work on that area specifically. As artists, there are still people who believe art is magic and that they either have the magic already or they wait for it to come to them in their sleep. Blows my mind. Granted, there are myriad things to work on and get right in order to make the kind of art one wants to make, but if you don't pick out the specifics and apply yourself to them, you might find yourself just waiting on magic.