Okay, for starters do I think that porn in itself is dangerous? No I do not. Porn in itself can never be dangerous. The danger however lies within how certain people perceive it and later on act upon it. In my opinion it bottles down to the fact that some people can't separate what is real and what is not real.
Now, I could go all saint-like, and try to fool everybody without actually doing so, and just deny ever watching porn.. Yeah... as if. However, porn have never really been about fantasies for me.. It's been a way for a quick release of tension between girlfriends and if you need to release tension overall. Although porn is strictly necessary I think I speak for a lot of others when I say it makes it easier.. Have I been damaged by watching porn? Not in the slightest. However I can see the danger if and when it goes overboard in more than one way..
People have different kinks that make them tick, but there are some things that simply shouldn't be allowed. If a person was to watch a lot of the really heavy dominance porn for way too long, then yes... if they have those tendencies already and have a problem with separating reality and non-reality then yes, they might become a danger to society. However, with that being said, the same would apply to movies, games, songs etc..
--------------
And in regards to whether or not it's a form of violence against women I call sexism. Is it any more so against women than their male counterpart? I mean come on.. Normal... hetero porn. A couple having sex, is that regarded as violence against women? Without having ventured too far into it, not having read the full thing, I daresay this author is crying wolf. My assumption would be that she found some gruesome form of porn (which shouldn't even be allowed to be rated as porn but enough about that), saw the female "lead" (yes, I use that term very loosely, you know what I mean.) being abused by the very dominant male lead and then wrote it off as "this is porn."
In regards to Martin Daubney's own theory or opinion I'd agree to a certain extent. I believe porn could be used as an outlet for all sexual fantasies but at the same time that does not always have to be the case.
-------------
Changing the way the population can access porn is in my opinion wrong. Effectively it would be a new way of tracking people and their activities. What's to say the next step won't be to track all form of internet activity the very same way. And once we're at that point then we're not far from absolute censorship. Opening the floodgates where they're basically saying "you're not allowed to do this and this" we're not far from having activists ban more things. Anything deemed possibly harmful would be shut down. And it would be based on their opinion.
Opening up for religious activists among others to effectively shut down anything deemed inappropriate.