I'm sure that's part of it. Antifa is definitely not well structured, and anarchists could probably be opposed to any official organization.

Let me put it this way, the post talks about a journalist who investigates antifa, which the op of this comment chain mocked because they're not an organization. But, this is an argument of semantics, and the post didn't use that word to begin with. Regardless of what you call antifa, he's trying to investigate and see what they're about.

It's a very dishonest way to deride people. If you don't mind me asking, if you don't think the word organization is appropriate, what's better? I mean I just say group, can't really be wrong going that general but it also doesn't say much. Like, when you said "people who participate in Antifa...", what type of thing are those people participating in?

Organizations do not necessarily require structure, association is a synonym for a reason. Decentralized organizations and associations are a thing. Decentralized workers solidarity movements and co-op/community strengthening initiatives can be/are "organizing" even if no one is in charge. You don't need to be a member of a union or an official neighborhood association to be part of an organization, there just needs to be general or vague common intention among a group and something of a shared identity. You might not get as much done a fast when not structurally organized, but you also don't not exist if your not a card carrying member. I don't understand the desire to divorce Antifa from being an organization or even existing. It's like saying that the Deadheads aren't a real thing because no one was directing the vast majority of fans who packed up and followed the band across the country.