I think things could also 'creep' in the other direction where the group communication becomes overwhelming. The article mentions that someone actually sold an item through the WhatsApp group. My worry would be that the WhatsApp group becomes and meetings turn into Craigslist, where it's people looking for dogsitters and Buy Nothing posts.
The point, if I have one, is that editing and saying no, especially with the technology, will help the group stay together. In person, obviously, neighbors can talk about whatever they like.
In my opinion a broadcast/newsletter would be the better fit for group communication.
The first book I thought about from this prompt is The Fountainhead. It's fiction and was written in the 1940's, but is very relevant to modern times. Very well written and in my opinion this book is better than Atlas Shrugged.
Replit for the website (he did the first 80%), Gemini to make the flyers and he'll be walking the neighborhood and talking to neighbors.