I've just vouched your comment. Not sure why it was removed, because you're right, games that are primarily immersive sims aren't being made as much by AAA studios now. Some mechanics are integrated into open world games to varying degrees (you could argue that BotW/TotK take so much inspiration from them that they might count, but to many people a replayable mission-based format is an essential part that is missing in them). There are some indies in this space but they're rare since the concept is difficult to develop around in the first place, given how you have to account for so many different edge cases and routes that the player can take.
Immersive sims have always been something of a niche genre, because they tend to have a negative difficulty curve: the player is very weak and lacks powers at the start, but becomes more resilient and more capable as the game goes on, often at a much sharper curve the game's difficulty. The result is that new players tend to be turned off and give up relatively quickly.
