I always checked the harbor for unlocked boats and took them on joyrides.

None of these experiences would be possible in a "WoW clone" MMO. Only with the freedom of an immersive sim can these memorable moments happen.

We could do it in 1999. Why has no one done it again? Why isn't there a BotW-engine MMO?

I think Star Citizen might be the closest thing. It’s certainly unparalleled. There is an interesting talk with the techtool guy from last Thursday.

https://www.youtube.com/watch?v=mmxmkx87qcE

Because this style of game appealed to two clusters of gamers. The first one is small and niche, and thus not profitable. The second one are the griefers who only want to play if they have victims available, which isn't going to happen in a small & niche game.

These kinds of games *do* exist, they're just, well, small & niche as they've learned to either build in protections against griefers and/or stay small enough to not attract notice. If you find yourself in the first cluster and not the second, you may want to check out the latest project from Raph Koster, aka Designer Dragon from UO. [1]

[1] https://starsreach.com