I read quite a bit and generally like Goodreads for what it is, but I agree that it's essentially not grown at all in 12 years. There are parts that are broken, there are features that are lacking, and it frustrates me to no end.

Many, many times I've thought of how I'd build a competitor, but it is pointless because Goodread's moat is too big: the integrations with the kindle go a very long way towards cultivating engagement (when you start a book, kindle will update your profile by default, it'll add your rating, mark the book as finished, all through the normal ux of the kindle).

There is no way, in my opinion, to overcome the handicap of needing users to manually update what is automatically updated by the kindle. And I can't see 'linking' accounts working because there'd be no incentive for Amazon not to block access from a competitor. And, frankly, the kindle is the only platform that matters, it likely has 95%+ of the ereader market.

Goodreads is bad because it is a monopoly, and that, frankly, sucks.