Btw that's the default behavior. You can change that. Most common reason systemd is slow is waiting on disks. But you don't have to (I don't). IME the hard drives and network mounts are the usual suspects. If they're not your main drivers mount then non blocking and they'll usually be up by the time you actually need them. Though if you're a server then you probably don't want that

Yep, and that's why a lot of old code has things like retry loops when a server starts in case binding the socket fails, or if a configured network interface/directory doesn't exist (instead of failing fast), etc. So much cruft could be cleaned up if we embraced this new world where we finally have reliable dependencies.

Sure your web server "started" 5 seconds after boot, in that a PID now exists for it, but that doesn't mean it will serve a web request if dhcp hasn't finished yet. `/etc/init.d/nginx status` tells lies on those old systems.