Well instead of a single-player game like Skyrim, let's compare apples to apples.

World of Warcraft has just released its 6th expansion, Legion. In the advertising and general hype train for the expansion, Blizzard talks about the Broken Isles, the Demon Hunter class, the artifact weapon system. All of these things require the player to be level 100.
Now we both know that Blizzard already sell these type of boosts and they are still loosing subscribers hand over fist, sure they do get a spike in player base when new expansions are released, but as history has shown it dwindles away, faster in more recent expansions too. I believe that this is due to a lack of solid content that keeps people coming back and takes time to break and the ease in how you can just level in a day or two heavy play.