Re: What a wanker
"its absence doesn't seem to have slowed down, for example, the IRA, the Mau-mau, the Stern Gang"
However, what we did not have at the time was random individuals with mental illness reading the output of those organisations on the Net and, as a result, going out and killing people. The three examples you mentioned were all territorially limited, while the Orlando massacre happened a long way from the Middle East.
There is apparently some evidence that organisations like Daesh are now finding it very difficult to infiltrate terrorists or communicate with agents abroad - the latter sometimes resulting in drone strikes. Using Facebook or Twitter to broadcast their views in language carefully crafted to stir up paranoid schizophrenics and the like, makes it possible for them to originate attacks without putting their own personnel at risks. It's a little bit like the Nazis indoctrinating kids via the Hitlerjunge so that at the end of the war they could be sent off, without direction, with Panzerfausts, thus providing human tank killers without risking the remaining regular soldiers.
There is a great divide between the EU and US over hate speech. The US thinks that allowing it will enable people to make up their own minds, but the evidence so far (Trump, for a start) is that many people are willing recipients. The EU has had a major war of ideologies in its territories in the last hundred years, which is why Germany has strong laws against far right propaganda. I incline to the EU view, partly because people like my father had to risk their lives so their families didn't end up in concentration camps.
I do think that Facebook and Twitter need to be subjected to tighter regulation, and if it turns out that their business model isn't sustainable, well, the US knows where it can stuff TTIP. Protection of a business model isn't worth the life of a single person, whether at a nightclub or a Labour MP.