Skyrim isn't a game by a lot of people's standards - it's an "Interactive Experience". It's just not challenging at all, and that's fine. It has a lot of good points.
1. Open world 2. It doesn't force you to take any particular path - I've played for 300 hours and never finished it. 3. Its very much a blank canvas that people can superimpose their own ideas on. Mods have done some incredible work there. 4. It's Grandma friendly. Easy to play. Nothing complicated about controls. 5. It has great worldbuilding and lore. 6. You could run the base game on a potato. (this is super important, too many developers underestimate how much this matters - it's one of the reasons Vanilla WoW was so popular) 7. It has solid Voice acting. 8. It expertly incorporates cultural tropes that we romanticize.
It sold 50 Million copies.
Elden Ring was a nightmare experience of incredible fun that was highly cultivated to hardcore gamers and it sold 20 Million copies as of last month. It's almost like they appeal to different markets.