A small example: IoT is now a must for modern houses with p.v. etc, Home Assistant is the most well known FLOSS solution. They suggest to deploy it via a docker image, so you need few Gb on disk just for it, relative ram etc. If you deploy via pip is just 321Mb, nothing else. Actually many system package managers support pip integration.
Not only, my entire home infra configuration is an org-mode file, easy to read, share, move just ~2000 lines, with a ks infra? I probably need around 4-5 time the lines in crappy YAML with constant babysitting to keep anything up to date. My actual infra is just two desktop, a laptop, a homeserver and few IoT devices (p.v. system, VMC controlled via ModBUS interface from the homeserver, few others goodies). The sole crappy YAML config for HA is four time* the entire NixOS infra config.
In a single click (on an org-mode link to tangle the config and on org-babel to run terminator and a script inside it) from one desktop or server I can generate a new custom NixOS iso for any other system, copy it to a tftp share for boot or on a ventoy-managed usb stick/ssd and manually boot the target machine. That machine will became the exact functional copy of the original one. With docker and classic distro? Well RH have kickstart is a bit less nightmarish than preseed and it's also limited, build a custom iso is a long process anyway, for Debian based is even longer. I do not know for Arch and co. A custom NixOS iso is just a single (or more, if I want them split) file passed to nix-build '<nixpkgs/nixos>' -A config.system.build.isoImage -I nixos-config=isoconfig.nix for Guix is just slightly longer.
With Plan 9 well, I do not even need an ISO since the infra is also the network... Countless of services and relevant network protocols are meaningless in a live plan 9, for instance sending emails potentially do not demand SMTP, the sender MUA just mount the network share of the recipient and save a file there. All is built-in in the system. Reading a website? The same: mount the exposed filesystem and open documents with your favorite viewer. Want something on another machine? Just open their relevant graphic display and there you go, no need for anydesk/bomgar/teamviewer/citrix/guacamole/*
But I can add more: no need for big cloud infra. These days we have enough bandwidth and computing power to have essentially all the real redundancies we need at home, that scale with the scale of the owner.