Starting with only 200 titles in the survey, for a final list of 100, seems off to me for starters. Every book surveyed has a 50% chance of making “book of the century”
Obviously 50/50 if random. But even if not random, I estimate 50 Shades would be 500-100,000 times more likely to be a book of the century using a list of 200 with it in it, vs an unaided open ended survey.
Or put another way “Every book surveyed” does a lot of heavy lifting here.