I've had submissions and comments of mine on this very account shadowbanned before I got some karma. It's just how the spam detection system works. So no, it's not just for bad actors, but for anyone an automated system suspects to be spammy enough. It's also easy to see whether your submission was shadowbanned by just looking for it while being logged out; only works if you know you might be shadowbanned though. So unsuspecting people who just got falsely flagged might never find out they are not being displayed to others.