"so we don't have clueless cops who shoot innocent people dead in tube stations?
or a history of massive uprisings such as the poll tax riots?"

Well yes. But they don’t arise from nothing without context. The poll tax riots came out of a background of a huge social movement against an attack on pretty much an entire class, hitting them in their daily life and pockets… hundreds of local anti-poll tax groups, demos, leafleting, door to dooring, 2 years of hard campaigning. There would never have been all those riots at the town halls or the Trafalgar Square demo/kickoff without this movement.

I too remember the 80s. But all the sabotage actions like Stop Business as Usual, attacking fur shops, gluing bank doors, smashing windows of Barclays etc etc, while being fun, and pissing off the local shopkeepers/bourgeoisie, made little real financial impact on multinational capitalism… And didn’t start any uprisings. Few uprisings, even proper riots, are started by activists on their own. If we genuinely want to overthrow class society and turn banks into playgrounds and dancehalls it’ll need more than small groups of moonlighting Zorros, it’ll take huge widespread questioning of the way we live under this society and a willingness for people to act on that, both constructively and destructively. This may seem possible in some places, although kind of distant in Britain at the minute (witness that unlike in Greece or even the police shooting of Cherry Groce in 1985 not a mile from Stockwell, the shooting of Jean Charles de Menezes didn’t even start a riot). Maybe the uncertain times we are entering will bring it on… maybe not. There’s nothing wrong with a bit of autonomous sabotage, but on the flip side, most of us also under this society DO need access to cash in banks to survive; (unless we have rich daddys like some of the insurrection now folk I have met).
All those who say we can all survive by eating skipped food - food doesn't grow in skips, its there as a side product of the consumer society that exists. Without that it wouldn't be there. Calling those of us who don't live entirely without paying for anything stooges for capitalism might make some people feel morally superior and free from this social system, but you aren't.
It’s worth picking targets that people identify with but that don’t actually make life harder for others of us.

Its easy to class anyone who disagrees with you as a cop or ‘intel’, but unhelpful. Good way to increase divisions, which serve s whose purposes? In fact most provocateurs I have come across are always the most keen to encourage illegal actions and draw others in to sabotage, violence etc… This isn’t to say everyone who does this is a cop, but it is an established tactic.

What’s a troll by the way?

I can understand the appeal of wearing a balaclava, painting some graffiti and becoming an "activist" (got to have a cool name for themselves - Anarchist sounds really cool). Going on "missions" whilst renaming anonymous is all a bit James Bond and obviously more appealing than going to the job seekers meetings to find out what a CV is. And their special little codes like solidarity something-something are really cute. But, sadly, its all a bit little boys i-want-to-be-a-ninja-turtle sounding.

There is always going to be people who blame the government for not handing them everything on a plate. Always going to be people who are happy to live on scraps like domesticated animals. This is why I now absolutely refuse to give money to the homeless anymore. I'm too worried I might be giving it to an "activist". Take away their sign-on pens. Stop giving them scraps. Lock down the bins and skips. See what happens when their tummies rumble and their bleating falls on deaf ears.