Yeah we used to call it "standalone mode", it was pretty neat but really confused users (it would auto-detect whether to go daemon mode or not, so behavior became contextual and hard to troubleshoot).

Yes, managing communication or other centralized resources is harder that way which is a challenge for "embedded Docker". Rocket does not have this problem because it relies on systemd to manage all this centrally under the hood. So you get "daemonless" as long as you sweep everything under the giant systemd rug :)