Systemd is a large piece of software. There are ways to make it smaller and disable various modules for it, but usually by default it’s very heavy.

With a traditional init system, it’s just an init system, and you’ll use other other programs to do the other things. This basically means a chain of interconnected bash scripts. Perhaps you’ll run into some integration issues. Probably not though. It’ll be mostly the same.

There is no real advantage to this from a user perspective beyond a philosophical one. Systemd works quite well at doing the things it tries to do, but it’s the Unix philosophy to “do one thing and do it well,” and some people care very deeply that systemd does not follow their interpretation of that philosophy, and that’s certainly a fair reason to not use it.

However, if you’re not having problems with using systemd, I’d say don’t bother switching.