>>53474922,1I'm being unclear here, so let me rephrase and expand this.
The thing you're complaining about has been going on since day one. "A bunch of people in IRC, or a lone autist, decide that something's funny and post it all over the site" is how nearly all of the well-known oldfag memes happened.
Everything you can do about the former will make things worse. No degree of surveillance and user abuse, up to and including actual fucking pay-to-post username bullshit, can definitively tell you whether people are coordinating in other channels. Coordinating against other humans is the oldest profession, and you are not going to solve it with a fucking PHP script.
>but it can identify more than zero of such cases It can identify the ones that are just a gang of lads having a laugh, and allow you to forbid them from doing that, yes (more realistically, it can give you some noise that you can then scheissanalyze to allow you to label any set of users you don't like as Organized Shitposters and thereby worthy of banishment). Iterated, this bullshit eliminates all of the obvious coordination - that is, the non-professional/incompetent kind - and leaves all of the professional, skilled shit. In other words, you've removed all of the non-threats and created a totally false atmosphere of security, while leaving all of the legitimate threats that you are incapable of mitigating because they're disguising themselves. You have created 1, a selection pressure for super-manipulator hypershills, and 2, a field of sheep for them to prey upon.
Bonus second-order consequence! The technology, both digital and social, that the actual threats use will eventually find its way into the hands of everyone else. Thanks for turning imageboard culture into a poisonous forest-of-mirrors tradecraft clusterfuck! I sure do love having to live and post like a fucking woman.
It's easier to do things about the latter, which is appropriate, because doing them will make life even worse than doing things about the former. Individual posters are very easy to identify, which means that you can easily forbid them from forcing memes. This means that if you want to force a meme, you have to have a coalition, which means that all the memes we end up having are KILL THE OUTGROUP coalition-maintenance shit. In other words, /pol/ and commies. Thanks for ruining the fucking site.