Watch the documentary Bigmouth, (it's on youtube). It's a bit dated, but there is one underwater segment showing a fellow fishing and the bass mouthing his lure, including cranks, and then spitting them out. The angler was shocked, having not felt a single thing. Sometimes it happened multiple times per cast. Watching that video and others, I had the same eye-opening experience you did. Sure, line watching might help, keeping your line taut might too, but I don't think anyone (despite much boasting to the contrary...) can feel/see every single bite.