Stephen King's imagination is a dark and twisted place, to the extent that filmmakers must perform extensive surgery on his books when commiting them to celluloid.
Some things, it would seem, are just too disturbing for mainstream cinema, but as far as the horror master's fans are concerned, they're usually the best bits.
Controversy is just one of the reasons filmmakers might chose to leave certain scenes on the page. Some of the nightmarish stuff King has dreamed up over the years wouldn't necessarily work in a visual medium, and the sheer length his bulkier books makes streamlining a necessity.
Take the recent adaptation of his magnum opus, The Dark Tower, for instance. Its whopping great page count and high metaphysics made it basically unfilmable, and there's no way some of its darkest scenes will ever make it to film or TV, assuming there'll be another instalment in the future.
Even the new It adaptation that recently arrived in cinemas had to make extensive changes to the source material, despite director Andy Muschietti clearly setting out to be mostly faithful to the book.