To my knowledge, shadowbanning isn't really practiced on Reddit to the same extent it is on sites like Youtube. Reddit mods usually prefer the plain old ban hammer. On most sites, shadowbanning is mainly done so the person shadowbanned is unaware of the fact they're being phased out of discussion and won't throw a shitfit in response. It's not just about keeping up appearances, it's about keeping people from responding to censorship because they can't directly prove it's happening to them. Another benefit of shadowbanning is that it doesn't rouse any contrarian tendencies in onlookers like a traditional ban can.
But for the hylics of Reddit (including the mods), there isn't a contrarian bone in their bodies; seeing dissent visibly banned or otherwise openly policed only appeals to their schoolmarm tendencies and entrenches them further with the orthodoxy of the herd. It isn't enough for the people they disagree with to simply not be present, they need to see them ban-hammered and scolded with a snarky, witty takedown that owns the chuds. It's the carnal desire to see your enemies thrown into the snake pit but gayer.