I had 3 under 18months so mine have watched tv from an early age(2 hours or less a day,very rarely more). I found the benefits for me were immense, I would have gone insane without it and been far more shouty than I was at times.
To me a happy home environment was important, I neeeeeded the tv on at times to amuse 1,2 or 3 of them. Yes I could have left them to it but 9 times out of 10 1 would have bugged the others etc and I would have got v stressed when making the lunch etc. I never had it on as wallpaper noise it was programs I chose and went off when I said.
My dc only watched Cbeebies. I am an ex primary teacher and literacy co-ordinator. I personally feel it has enriched their lives as they have amazing imagination and general knowledge. Most of that is due to the vast amount of books we read but some is definately due to Cbeebies.
I've always read masses of books to them,we are all book mad and craft mad too. The dtwins(boys) have just started school now and they are romping through, lapping up the books they bring home. 1 was pretty much reading before school(self taught)and the other is pretty much the same. They adore reading to me,their teacher and themselves. They all have excellent powers of concentration.
My dc are awake 12 hours a day. I'm sorry but no expert can tell me 2 hours max of quality tv in that time is going to harm them when they spend the vast majority of that day romping in the park,on the beach and moor,at pre-school,reading books,doing crafts and playing with their toys,friends etc.
So I personally think that article is scaremongering, not surprised to see Sigman's input, he is on a bit of a crusade. However I do think screen time as a whole is slightly worrying. We don't have computer games(Playstation and the like)and computer time is very limited. They will never have any screens in their bedrooms. This is due to to me feeling more concerned about the latter-very fast images,poor content,sitting so close to a screen and the anti-social nature of it.
I think ' experts' like with most things are going completely overboard. Yes if it's on all day, very poor content,is on top of a vast amount of computer game usage and a child does nothing else ever I can see that it could be detrimental but if used sensibly which lets face it most parents do then I just don't see the harm in it. My dc and their friends are living proof of that.