You don't need any of the *arr stack, they just make media management easier for us hoarders with huge libraries. I couldn't imagine maintaining a collection of thousands of TV shows and movies without them. Every single arr program is a progressive enhancement over the "once upon a time" stack you mention.
Not that your old stack doesn't still work exactly how you'd expect it to, nothing's changed there.
Not that your old stack doesn't still work exactly how you'd expect it to, nothing's changed there.