The problem here is that they made a sequel to the 1980 movie... and not a sequel to King's book.

And, let's be honest, as good as Stanley's film was, it really had little to do with Kings novel. Almost The Shining in name only. So many changes were made, right down to the theme, that it barely resembled the book.

So, when they made the sequel to the movie, and not the novel, a lot of the elements that made the Doctor Sleep compelling, a lot of the plot points, and a lot of the twists and turns that made the novel worth reading had to be changed in order to keep continuity with Kubrick's changes.

The result is really kind of a mess. So much of what Doctor Sleep was referenced back to The Shining, the novel, that trying to adapt the script to the Kubrick film was, honestly, a mistake.

In the end, it grasps at straws and never finds a footing, making Doctor Sleep even further removed from the story it was based on than Kubrick's film was... with far less talent directing it.