Because narrative in multiplayer and "emerging gameplay" is terrible in my opinion. I want a well crafted game with a beginning and an end when it comes to certain genres. Racing, Sports, Fighting yeah those can have the online component and be competitive (I still want a strong single player experience)
I want a well crafted game , not being with "GamEEERXXX78" jumping around in a multiplayer lobby while the quest giver sends me to kill X number of enemies to gain xp.
You can have great gameplay in single player games as well. Single player games have been around for far longer than multiplayer games. I still like multiplayer games like arena shooters, that genre respected your time. Not skinner boxes like Fornite, but at least that game is funding my Epic games collection 300 and counting.