It looks to me like this is useful for these reasons: When sending; a single interface may have many peers configured. In that case WG needs to be told which p

It looks to me like this is useful for these reasons: When sending; a single interface may have many peers configured. In that case WG needs to be told which peer to tunnel the packet to or it wouldn't know. It's can be viewed as WG internal routing table, in addition to the ordinary IP routing table. When receiving; although the packet is proven to be from a configured peer, that peer may have used any IP as a source (referring to the encapsulated traffic). Even if you trust all your peers are who they should be this is a potential security risk. For example a peer may spoof its source IP to imitate another peer. You could patch this hole with iptables rules, but this way is more convenient and has a better chance of being correct since it's simpler to configure. If you don't want any of this I suppose you could just set up multiple WG interfaces instead, configuring only a single peer for each interface and setting AllowedIPs to 0.0.0.0/0. That should give you the same behavior as a what I think you mean by "real VPN".