a) Selecting a book, we want something at least one or two members have already read to make sure there's a good recommendation. Going by reviews has not worked well, it's better if someone brings the selection to the group because they have some personal stake.

b) Coordinating the schedule - you want to give people enough time to read the book but two months out the calendar is still volatile so often I have people drop out last minute due to meetings being schedule over, frustrating for everyone and apparently people don't want to tell their manager bookclub trumps work meeting.

c) Recruiting new members, we usually have a steady core group but want to beef up our roster to where we don't end up with awkward 2 people meetings.

Some of these issues don't apply with technical/business book meetings since it can be done chapter-by-chapter. We've done that as well and it's easier but usually after two or three chapters people drop off or lose interest in specific ones.

You could argue that your website isn't concerned with some of the above (e.g. people preselect books, then others show up automatically) but Goodreads and others already do the same for free.