It never really went away. Last decade is truly a golden age marked by the *arr suite of tools, most of them are better maintained than an average streaming app.
As with many tools there are forums (reddit, etc) and wiki's - you might start with an arr-wiki: https://wiki.servarr.com/en/radarr, your mileage may vary (I've been aware of the suite for years and talk with people that use them, but haven't felt the need myself so far).