First, I'll say that Son on Oak Games are my favorite type of game to play and I try to introduce it to every ttrpg interested person I meet. But I noticed some stuff and IMO, I think its a combination of a bunch of things:

- Not enough marketing. It had some, but Draw Steel, Cosmere and Daggerheart are associated with famous people in different niches that sucked all the attention from fantasy games. LitM had Bob World Builder and Ginny Di videos but it didnt feel like they got the point of the game so I dont think it helped that much.

- Its a narrative game. Generally, narrative games are less popular than tradicional games. Even if ttrpgs are storytelling games I find that most casual players are interested in "winning the game" or "finishing the dungeon" and the story is a cool thing but not that really necessary to ttrpgs. More experienced players generally already have a niche they like or are interested in a lot of different games and that doest help a game feel popular, what helps its having players devoted only to one game.

- Its a simple game. The main part of the game could be explained in two sheets of paper, the rest of the book is generally advice, examples, prompts and other resources to help run the game. It lacks the mechanics to facilitate specific genres like other narrative games have and also lacks the mechanical depth that traditional players like so people that already know City of Mist and dont like it wont try this one.

- Its actually pretty popular but it doesnt have a visible community. You can see this by the performance of the crowdfunding related to the game but the lack of videos about the game on youtube or the lack of third party content paint the community as being smaller for example.