No, Neighbor is not a scam. It's a legitimate service that can connect you with affordable storage solutions for a wide variety of items.
That said, with any sort of online marketplace, there's never a 100% guarantee that people will not try to use it in a predatory way. The good news is that Neighbor has practices in place to combat this.
On top of liability coverage, Neighbor also provides authentication services and encourages hosts to run their own background checks on potential renters.