Nextdoor isn't especially unique compared to other social media platforms. What does appear unique is its traction among highly localized user groups (i.e. neighborhoods). Both myself and friends found Nextdoor actually extremely useful in the course of recent home purchases, to get to know the target neighborhood and seek inexpensive repair/contractor services.

Given Nextdoor's very localized character, there can be unwritten context to users' posts not always present in other platforms like FB. Eg. very easy to imply "I know where you live" in a way the intended recipient may grasp, but group moderators do not. As another commenter said, having users click through some questions before committing a hot-headed posts seems wise. It would mirror a face-to-face interaction, i.e. "Did you really mean what you said?"

No idea, tho, on the justification for Nextdoor's metrics for reducing abuse.