Progressive stacking made its appearance at OWS though (along with creep call/response chanting that I'd only seen in weird christian cults up to then), which I'd pin as the genesis of the current iteration of IdPol bullshit. GG and its contemporaries are an emergent effect rather than a source.
It didn't first make it's appearance there, though.
This is the exact same thing as the Maoist tradition of "self-criticism" or "Speaking bitterness" essentially where "privileged" people(in the case of the former" would self-flaggelate and "oppressed" would condemn the privileged. This was cynically exploited by Chinese bureaucrats to execute people they found politically inconvenient or who stood in the way of their ambitions. This was really the whole purpose, as this entire thing was the bureaucrats' idea to begin with. "Cancelling" today is just a less lethal version of this, but it is the same thing in essence.
Arguably it has its genesis even earlier than that. At the 7th Congress of the Comintern in 1935, Georgi Dimitrov, the head of the organization, delivered a speech signaling the adoption of the "popular front". The essence of this policy was that communist parties in the west would stop trying to gain power and instead work with a coalition of feminist, liberal, worker, and anti-racist groups as part of a broad coalition against "fascism". It did not matter that there was no fascist movement in the US; then, just as Antifa is doing now, the CPUSA declared that the Republicans and their supporters were fascists who threatened "the gains of bougeois liberal-democratic liberty".
“The communists attack us,” say others. But listen, we have repeatedly declared: we shall not attack anyone, whether persons, organisations or parties, standing for the united front of the working class against the class enemy. But at the same time it is our duty, in the interests of the proletariat and its cause, to criticise those persons, organisations and parties that hinder unity of action by the workers.
The essence of the quote is essentially that one isn't allowed to criticize anyone who is "marginalized" or "oppressed" no matter how self-defeating and exceptional they are, since this would be 'letting the fascists win'. It was even CPUSA policy that in the fantasy scenario of them coming to power that they would balkanize the United States along racial lines and create a new black nation in the south.
Still, a good chunk, probably a majority of the American far left took its politics more from an early splinter of the CPUSA, the SWP(and its splinters) and weren't heavy into the identity politics. It took Maoism, the SDS, and the New Left of the 1960's for identity politics as we see it today to really start. Many of the grad students who embraced Maoism later abandoned it and jettisoned the Marxist aspect of it in favor of a pure identity politics, this was the background of the intersectional theorists like Krenshaw who created the theory that people like Antifa base their politics on. It was mostly a thing in Academia, however, until just recent years. To give you an idea of just how tiny and insignificant the old Marxist left was in the US, a decade ago the largest revolutionary Marxist organization in the country was the ISO, which had(it claimed) 2,000 members. In total, adding up all the sects there probably weren't much beyond about 10,000 self identified communists in the US as of 2009.
In comparison, something like the DSA, which has a heavy crossover with Antifa, has over 40,000 members. The old left is pretty much extinct, even the ISO just disbanded quite recently. They're all jumping ship to the likes of Antifa and the DSA, an organization so autistic that they banned clapping as "ableism" since it would be "upsetting to deaf or autistic comrades". All of this shit we're seeing today is based on the intersectional theorists who came out of the New Left, but as I said earlier intersectional theorists themselves are genealogically derived from Maoism, and from there, Soviet style Marxism-Leninism. This is why SJW's behave so similarly to how you'd expect Soviet bureaucrats to react to dissent and disagreement, it's not a coincidence, but the cult-like thing is a distinctly Maoist thing in origin. Look up Bob Avakian and the Revolutionary Communist Party, there's some lulzy stuff but you'll see that what we have now is just a rehash of shit like that.
I was present at a few OWS events in 2011, and frankly I did not see anything that really resembled the identity politics we see today. Neither did anyone else I know who went to different events elsewhere. I don't deny that some of that shit was present in some places, but I'm skeptical it was as prevalent as you seem to think it was. It wasn't until a few years later, 2013, or so, that I first started hearing about whacky idpol as a regular thing. I heard from some guy I knew in the Spartacist League that they had gone to a BLM rally somewhere in Michigan, but the group of people that went included both whites and blacks. The BLM organizers told them that they had to segregate themselves based on race and that they couldn't march together, at which point they were told to go fuck themselves.
I'm not really seeing a connection here between OWS and GG either. OWS was a handful of actual workers, mostly students, some wealthy liberals, hobos, junkies, and a random assortment of others across the entire country. GG just involved a handful of exceptional individuals, con artists, and neckbeards who bickered almost exclusively online. Any similarities are just incidental IMO. The obsession with weaponizing troon degeneracy also isn't something that really happened before GG either. The far left before the rise of Antifa and the election of Trump(or GG, at the earliest) didn't really give a shit about trannies, and when they did bother noticing them it was usually negative. Revleft, the main online hub of the far left before Reddit became popular only had one active troon on it. I know of a few of the 'old' generation leftists who trooned out, and each of them trooned out after Trump's election. Every single one. Not a coincidence.
TL; DR of it is that Antifa is just a highly autistic replay of things we've already seen play out multiple times, going back as far as to the 1930's in some cases.
I think the real question with Antifa is how long they will be tolerated before they become a liability to the Democrats. So long as they direct their energies exclusively against "fascists"(IE anyone to the right of Alexandria Ocasio Cortez), they're useful to the Dems. That changes if street violence starts spiraling out of control. Plus the whole thing with Black Bloc tactics is that any cop can just dress up in black and start trashing shit and instigate violence giving the police a pretext to crack down on them. Apparently Antifa's supporters are too exceptional to even think about this.
It will probably happen sooner or later, but in the meantime their incredible levels of autism give us plenty of fodder to laugh at.
