It's not as much a limit of man as there is a limit of the media itself.
Of course you might work something out, but it would be a compromise leading to a lesser result.
What make Lovecraft so great to me is that I can connect them to the real world in a sense, connecting the stories/testemonies of the people within the tales as something that really have happened.
While if I saw a movie, it would be a movie of these stories.
It's not the words of the person in question, but an adaption of them.