NixOS does enables this to a degree, for example with nixos-mailserver[0)].

It would be nice if it could enable people with little sysadmin experience to self-host easily, but right now the bar for using NixOS and configuring these projects is still pretty high. Still, with enough work I imagine it could be possible.

[0] https://gitlab.com/simple-nixos-mailserver/nixos-mailserver