How many public discussions have you participated in at a coffee shop? If you have something to say and you go there and start trying to chat up anyone who walks in the door, what response do you expect from the proprietors?
If you go to a park which is within 10 miles of the median home, how many people do you expect to encounter there at any given time, especially in the heat of summer or cold of winter?
You need indoor spaces that don't have some private commercial operator, like community centers or hackerspaces, but those are the things that get priced out by high real estate costs.
> People also hang out at each others' homes.
You move to a new city and want to meet people. Are you expecting many strangers to invite you into their homes without introduction?
> Moreover, supply of public spaces increases when there's demand, much of which is being soaked up by social media.
Social media costs time. Physical spaces cost even more time (since you need to travel there) and they cost money (to cover the rent). What happens when you then make the rent high?
> Even social media can be meaningfully distinguished in terms of design features.
So is e.g. Usenet social media or not? Does it matter if it provides ordering options other than search by date?
> They've all since morphed into toxic cesspools of social comparison, parasociality, polarization, disinformation, and other problems.
Because those things increase engagement and the central middle man gets paid for increasing engagement.
> Interoperability/federation doesn't solve those problems
It removes the perverse incentive to design things that way.
> most of the interoperable and federated solutions actually perpetuate them, because the problematic design features are part of the spec.
Then why is Neocities or "add a Bluesky comments section to your blog" so much less toxic than Facebook?
The primary thing driving toxicity in certain federated networks is when they get a huge influx of users after some incumbent social network gets into the news over political suppression, because then a mass of the target's partisans try to switch to something else in protest and partisans are toxic so if you get inundated with disproportionately partisan exiles you've got a problem. Which doesn't happen if you federate the whole main network containing the majority of the population including moderates and apolitical subjects rather than disproportionately one side's most excitable militants.