Modes control which people and apps can trigger a sound/vibration, but also offer the option to hide the silenced notifications from the status bar, pull-down shade, and dots on app icons. I hide them from the status bar, but not the pull-down shade so that I can manually check if I want to, but don't see them at a glance.
I'm not a heavy user of this feature though; I mostly don't install apps that have spammy notifications.