This is certainly the promise and potential of getting online social activity standardised to a protocol shared by just about any online social platform.
Thing is, I'm not convinced the current structures of the fediverse are really equipped to bring about the desired stuctures. And, without knowing enough about the ActivityPub protocol, I can only fear that the issues may run relatively deep.
The fundamental problem that hasn't really been "solved" is that an online space of any sort needs a computer that it is plugged into the internet all the time ... a server. This requirement imposes a centralised type node on what structures can be created. We can see this clearly with the fediverse in the way that instances are so dominant ... so many of your choices as a user are bound up with your choice of instance ... moderation, IRL-people-community (if there are distinct communities on your instance), reliability (how good are the sys admins?) and what kind of platform and therefore social media you use (is it a lemmy instance or a mastodon instance).
Once you realise that IRL-people-communities are rarely fostered on distinct instances (on lemmy there's a bit of this but the whole thing of federating lemmy-communities is really about allowing these to grow across instances ... on mastodon I'd say it's mostly not common) ... and that a lot of the defederation stuff is either fairly obvious moderation stuff or grey-zone stuff that usually divides the affected users ... it becomes apparent I think that the instance as a hard-wired coupling of many aspects of the social media user experience is more of a hurdle than a feature.
Over on BlueSky/ATProto they're doing something that may turn out to be interesting by trying to remove this imposition ... but the solution is still bound by the need to have a centralise-ing always on server ... as they have big giant firehose servers that everything else relies on ... of which only a few a likely to ever exist ... thus creating another imposing structurally centralised reliance. They're hoping that all of the flexibility will come from all of the things that depend on the firehose, but still it could turn out to be an issue.
Broadly speaking, the ability of the user's choices to organically grow and connect the open social space that the article talks about is still very restricted IMO. And there is probably a fair way to go technologically before the foundations are even there.
I've seen it mentioned by a few people, and I've thought it myself ... that the fediverse as we know it is mostly a prototype and the promise we're all after will most likely come only once we've moved on to something new. If this is true ... we're in an awkward position right now where there are a lot of people who believe in these "promises" and that they can be realised on the fediverse as well as a lot of people who have built stuff on the fediverse, have stakes in its success and are really advocating that this is "the solution" to the point of resisting calls for doing better and new things. Sadly, this sounds like the recipe for some bitterness and failures to occur which, IMO, runs the risk of deflating and removing the momentum behind the broader mission of realising what the article speaks about.
Part of the problem here is that the big-social mega-corp monopolisation of social media was so bad and so long lasting that we've atrophied the muscles of social organisation. Collectively and behaviourally, we don't really know how to do this or how to talk and think about it (personally I think the conversation around Threads and whether to de-fed shows signs of this).