Diversification. Theoretically most of the nodes are owned by different people, and every connection will randomize your node list route between them, making it difficult to track, unless most of the nodes were owned by one organization. With VPNs, all of your connections are through servers owned by one company, identified by an account ID.
Isn't using Tor browser trusting a group of unknown people as well (nodes)? I hear all the time theories that Tor is a giant honeypot