It's trite, but I think a part of it is "because the internet happened" - and I don't mean just today's enshittification era but also the "good old times" everyone seems to remember fondly here. At some point, the internet was full of that kind of community spirit that you described, but of course this meant that people were more likely to direct their energy to online community building than to real-life stuff. And unfortunately online communities didn't always teach the skills that offline communities required, and also probably contributed a lot to the "consumer mindset" the OP warns against...