Multiplayer repeats the same gameplay mechanics, but not the same gameplay per se.

In singleplayer, you're generally 'fighting' against AI. Your opponents never learn. They never do anything different. It's always just the same thing, with little bits of variance.

In multiplayer, every game is completely unique, because you're playing with humans. They learn, they react, it's social. It's always fresh and fun.

It's like hanging out with friends. You're always 'doing the same shit', but it's always fun because it has a human element.

And that's just it, the human element. It adds infinite depth and complexity. I can enjoy playing something like CSGO to the end of time, because of people.

Singleplayer experience are just so fucking shallow. I feel like I'm exploring a grave yard.

A few hours is all it should take to tell a compelling story, introduce gameplay mechanics, and provide an incredible experience.

I've never once played a 20 hour singleplayer game and thought "I'm glad that was 20 hours".

Portal 2 dragged on.

SOMA dragged on.

Mario Odyssey dragged on.

etc etc etc

These are great games, and i enjoyed them, but they felt like they were long for the sake of being long, because people get upset if they don't get 20 hours of gameplay.