The thread is from 7 years ago but it's still a question for me too! In my personal experience, directories and bookmarking websites make web crawlers to crawl and index more pages of the website, but not much impact on the website rank on SERP.
Dead or Kicking is one example, this website has the database of thousands of celebrities death status. It shows if a person is alive or not, their cause of death, date of death, location of death and much more. Because they have a huge database, having all the pages indexed is a dilemma.
Would love to hear your personal experiences on this too! Thanks
