Games you beat once and never touch again and games with a competitive multiplayer with persistent free content drops are not comparable. Thread OP doesn’t understand this.
Nope. I understand that perfectly. Games you beat once, and never touch again have unique level design, enemies, puzzles, quests, gameplay, story content, dialogue, etc. They offer up quality over quantity. They offer unique experiences that are memorable. Multiplayer games are often just hundreds of hours of the same old same old. And to make matters worse many of them are just shooters, a genre which has gotten horribly stale over the last ten years. You simply can't compare a game like BotW, GoW, Spider-Man, Super Mario Odyssey, etc. to another shoot-game, with a multiplayer mode. If I play Odyssey, I'm taking over a T-Rex, or becoming a gliding lizard, or something else crazy and new, and interesting and fun. If I play one of a bazillion shoot-games, I'm just doing the same old boring gameplay I've done in a bazillion other shoot-games.
And like I said before, multiplayer games don't take very much effort to make. Let's take Halo or Halo 2 for example. Two games I know we've both played. How many assets do you think are in the main campaign of Halo? Now how many of those assets made it into multiplayer? How about for Halo 2? An asset can be a sound, 3D model, animation, or texture. Now let's ask ourselves how much level design was put into Halo's single player campaign. Same for Halo 2. How many square feet does the entirety of Halo's single player campaign consist of? How about Halo 2? Now, how about coding? Is there AI in Halo's multiplayer modes, not including co-op? How about Halo 2? Are there carefully coded scenarios in Halo or Halo 2's multiplayer mode, designed to challenge the player? Anybody without bias is going to answer that the campaign modes of both games have vastly more assets, programming, and level design than the multiplayer modes.
Now remember that Halo 1, and 2 both have 11 hour long single player campaigns. That remains pretty true for Halo 3, 4, 5, and Reach as well. Now keep in mind that single player games like GoW, or Spider-Man, or GoT are easily twice that length. If you're a completionist those games can balloon to well over 50 hours of single player content. Now keep in mind that we've already established that single player content often takes way more assets than multiplayer content. The level of effort that's put into a multiplayer shoot-game like CoD, Halo, or Gears, is insignificant compared to the level of effort that goes into many single player games.
So like you said. There's no comparison. You just had it backwards.