I disagree.
I'm a member if many local communities on Reddit and Facebook.
Where I live, Facebook Marketplace is _the_ place to go to buy and sell used goods. And it is absolutely hopping in my community. So much waste is averted from landfills due to the platform Facebook provides, which has good search, and a reasonable UX.
If all we had were the old school classifieds in the newspaper, I doubt nearly as much activity would happen.
HN just loves to shit on social media and lament the fall of old school local news, but I think that's just rose coloured glasses.
Through Facebook I do local second hand shopping, I discovered and am and member of several local niche sports and activity groups. And I see local news through the eyes and mouths of locals talking about it rather than what the one or two employed local journalists think.
If all you do is scroll /r/all or your Instagram feed than sure you're not getting local info, but you get what you consume.
And I say this as someone who doesn't like Meta/Facebook and would delete it in a heartbeat if there was a viable alternative, but the matter stands it _does_ support and encourage local communities and content in some places.