The OP is onto something.....

Many do not play multiplayer games, for the multiplayer aspect...Eevn though it is always there.....

I mean.....Fortnite is a multiplayer game, but there are streamers who have solo streams 90% of the time....

I like Streets of Rage, cause it is a cool game.....Which just happens to be multiplayer.

I feel like, people look at the term "Massively Multiplayer Online Game" and get it wrong, 100% of the time..........

"Massively Multiplayer Online Game" is simply telling the buyer the game is online, and many players are playing among you....even if you are not in a designated party. FATES are one example of this. You are pretty much solo, but you are really not............

It has nothing to do with how one should play, but how the game is designed. The reality is, you are playing among a "Massively" amount of people just by walking around town......That is all that term means.