I've traveled in so many countries, and the ones with the best fiber in the world can't guaranty a stable ping for the entire day.

This is what makes so many online games frustrating. I played MOBAs for a long time, and there is nothing more irritating than losing because you didn't get an information at the right time.

Now a non multiplayer game is not real time, so you can put mitigation measures in place, but it can't fix everything, especially for games where the rhythm is important: plateformers, FPS, racing games, etc.

We put up with it in multi-players game because there is no alternative.

But are you going to tolerate than sometimes, randomly, you are going to die because the network had a spike in ping when playing Mario or Cod when you could play comfortably on your TV locally ?

Remember the joke: videos games don't make kids violent. The lag does.