Consider the source: Cressida Dick, and the Met Police. Look into their history, conduct, competence and attitudes, and you’ll understand why. I’m decidedly not a fan of much social media, but this is the usual deflection you get from the usual sources. Dick is so far to the authoritarian Right that she walks with a limp. She’s definitely not going to say that years of failed social and economic policies have predictably led to a rise in violence, but blaming social media? Oh yes.
Note that most knife attacks are during the commission of another felony, usually robbery. Unless social media is somehow being used to coordinate robbing people, you can safely dismiss Dick’s claim.
There is also element of drug prohibition that brings violence. I think I have never heard this on any debate about the problem. It seems like there is a media embargo to talk about this correlation.
Some background on the recent history of violence in the UK might help too. http://www.bbc.com/news/uk-42749089
Note that most knife attacks are during the commission of another felony, usually robbery. Unless social media is somehow being used to coordinate robbing people, you can safely dismiss Dick’s claim.