New ask Hacker News story: Ask HN: Why hasn't an IMDB/Goodreads for podcasts emerged?

Ask HN: Why hasn't an IMDB/Goodreads for podcasts emerged?
3 by jonathanrstern | 0 comments on Hacker News.
A few people have tried to build this (e.g., Podchaser). But nothing has come close to being really successful. What's the hold up? Is this one of those seemingly "good ideas" that's just not that good?