Same reason why Ubisoft isn't just making another Balatro. Industrializing culture isn't (yet?) a solved problem.
The Beatles did only take a few days to knock out each of their earliest LPs. However, per Wikipedia, "the group spent 700 hours on [Sgt. Pepper's Lonely Hearts Club Band]. The final cost [...] was approximately £25,000 (equivalent to £573,000 in 2023)."
So, actually, envelope-pushing cultural landmarks typically do require a lot of effort and money to complete.
But, of course, making games is hard, and sometimes they fail. And now the free tools are getting really good, and smaller studios are becoming increasingly competent. Will we soon see the big ones fall? Their only way to survive is to keep going bigger, escaping the smaller studios to a place they can't reach. Now we have AAAA games. But is there a limit where players stop caring how many As a game has?
[0] https://en.wikipedia.org/wiki/Electronic_Arts#EA_Originals
Enter: parasitic storytelling https://www.youtube.com/watch?v=gFxu3Q71NvE