Is There a System D?

In the past, i know there used to be applications that were written where the application itself would background itself. And basically that would allow you to run it in the background without something like a system d. And so it sounds like now what you should do instead is have your application be built to just run in the foreground. Your process manager, like tem d, can be configured to handle re starting it, which user is running it, environment variables and all sorts of different things.