A pretty nice use case I have for socket activation is for isolating containers or applications from the host network.
The great thing about socket activation is that opened sockets carry over even if the application/container unshares into a different network namespace!
It also works great with Podman pods with networking in the pod completely disabled and, as those are host sockets, does fully retain the connection info of peers (so logs are not just uselessly containing the gateway IP, depending on the container network config)