This is not correct. Wireguard establishes a tunnel between peer A and B, and its simplicity stops there. Tailscale does tons of complex networking, filtering, nat traversal, DNS, file sharing, etc. Wireguard is a small part of the codebase today, which has grown a lot.
It’s a bit like saying Dropbox is just a GUI on top of TLS.
It’s a bit like saying Dropbox is just a GUI on top of TLS.