Deviant Art is definitely one of my biggest distractions now..I go on and check my notifications for 2 minutes and end up spending almost an hour just browsing... This may spell disaster for me in the future
Watching television may affect your ability to concentrate thanks to it shoveling information at you faster than your brain can process it but no, I don't think DA can cause concentration issues. Sure, being addicted means you'll be distracted from other stuff because you have the constant need to refresh your page or something similar but that's what addiction is and by that logic, you could say alcohol, coffee, candy and soda "make" you adhd, too.
I come here a few times a day to check my inbox, perhaps browse through the forums and check whether there're any commission opportunities at the job offers -forum. I spend more time every day trying to prevent my son from destroying the keyboard and tablet than I spend here.
I have adhd, and I'd say drawing only calms me down. Everything I'm interested in - total concentration, you could bomb the house and I wouldn't notice. Kinda like many others with adhd... I don't know about that dividing time -thing, though. I just turned twenty one so by all means, people think I should be destroying my brain in a bar and being all sorts of stupid right now.
The only internet-related work-load I have is because I own a group, being a beta-tester doesn't contribute to said load in any way.
Heh, I have ADD(not relaly and 'H'), but dA and computer in general are a distraction.
In regards to artists being born with it, people with ADHD are known to be very creative!!
So, artists aren't necessarily born with ADHD(or "develop" ADHD from being an artist), but people with ADHD develop into artists often. =3 Mental health problems=more creativity. Though not every artist has ADHD. xD
I joined to take part in the forum discussions, and that's primarily where I stick to. Of course, I've also been around here for ten and a half years, so not much is new to me. So, no, I can't say that I'm terribly distracted by dA anymore. Coming here is more like a daily habit.