The feature I liked most in goodreads, was that it would send you a monthly email with "new books by authors you've read". It would send it at the start of the month, which was not actionable, but if you'd just wait a few months reading it, it was easy to see that LE Modesitt Jr finished another book in the series I enjoyed.
They stopped sending that, now it's a "here are some books we want you to show some interest in".
I got a bookwyrm account, and apart from not knowing all the books I've read, they also can't tell me what books have come out recently, by authors I enjoyed in the past.
I'd think that would be a basic part of any book collection tool.
Does it have a relationship mechanic though? I always assumed it was just about equipment and using that.