I don't think there's anything monopolistic about Goodreads .. we just convince ourselves of it. But as we can see here, people would be highly willing to try out some competition.

It's a lot harder than people give it credit it for as well, I imagine. "why don't they get a recommendation engine already" ... that's the secret sauce of companies like Amazon and Netflix who have a financial interest in every successful recommendation. Goodreads doesn't have a profit model in place afaik to support honing the engine to that degree