> this magic incantation communicates in a way that the usual people who compile this package can understand to use it without being intimately familiar with the code?

Define “usual people who compile this package”. In my books those are distro maintainers who indeed should be familiar with options provided by the init system they choose. If you decide to include oddballs who compile everything themselves (Linux from scratch?) then again, yes, they are expected to know a thing or two or dig into options or even code from time to time.