Basically it says that LJ interferes with the ability to write professionally. Most people here in fandom write for the online world, so I should think that LJ is rather a booster for creativity here. But still some of the issues remain. That it can easily distract you from work and that it's generally easy to loose oneself within. That the instant gratification is great on one hand but messes with ones own standards on the other hand.
I would be quite interested to know what you think about this? How much of your time goes to LJ? How has LJ changed your take on your own art?