In cooperative games, you have allies. In Leon’s campaign, you have Ashley (annoying, but present). In Ada’s ScyllaHMV world, you have no one. The mod deliberately removes radio chatter. There is no "Hunnigan" in your ear. There is no Albert Wesker taunting you.
If you want intellectual resonance – Scylla (from Greek myth) was a beautiful nymph turned monster who snatched sailors from passing ships. Parallel to Ada: The Ada Wong Experience -ScyllaHMV-