From comments I've read on different works done on DeviantArt, my impression is the regulars from there do seem to be the easily amused person type so they hardly give a chance to other works aside the first ones they saw. Newgrounds does have its good share of those too, but the more critical and analytic users appear here more often and help far more from what I've seen so far, so.. maybe it's true.
Ironically, following that belief, I can see why many artists transition to DeviantArt or come back to it, maybe they felt too harsh the critics they got here. Though there's also the ones who were simply unlucky to be flamed constantly by the dumb guys that stay around here and which sadly also save junk submissions.
mrRedux
Much more influential than the Deviantart community?
daigonite
I would say so. I found them to not really help out much at all. Most of it was just "THAT'S GREAT" along with tops 500 views on my more serious works. It appalls me that WELCOME TO DEVIANTART, something I literally whipped together in 50 minutes, has more views than REVENGINEERING did before I took it down (about 1,600 compared to 350). I found an audience here as opposed to deviantART, and they're listening, and helping.
That's a big reason why I moved.