Can you explain how exactly it would add confusion?
You must be new to the Internet.
See, there are going to be players out there looking at those single/multiplayer prompts and thinking "Uh.. well, I'm starting off singleplayer but I might want my friend to join me later.. but I might not. Am I locking myself into a choice by choosing one of these now? I better go ask on the forums..". That's "confusion". It also addresses your "who cares" question.
Remove an option and you'll have the same number or more people asking "where is the multiplayer option?" / "where is the single-player option?"
