It's too bad, I think idea of organizing a social network based on proximity and centered around community information is a viable idea, It's just that NextDoor is doing that with our worst instincts.
I have only seen a little bit of NextDoor, and please correct me if I'm wrong, but it seems to me to be more of how people are deciding to use the platform as opposed to NextDoor purposely promoting our worst instincts. Do you feel like they really are promoting the most inflammatory posts for the purpose of increasing engagement? (like so many of the other major platforms out there)
For me it is sad to see that there are so many people out there too quick to pass judgement on anyone that looks different in their neighborhood. But so far it feels like another example of how web platforms allow people to be more comfortable in expressing their true feelings, and while often disappointing, is a good reminder of the very different views people around us can hold.
I don't think it's necessarily intentional, but posts which foster fear (like "I saw a scary black person walking down the street") will naturally invite more engagement from users, and the site may respond to that by promoting those posts over less controversial content (like "my cat is missing").