When I was young, I joined the Doubleday Book Club for a brief time, then later the Book of the Month Club (also briefly) and later still, another club which I belonged to for more years than I can recall, until yesterday when I dropped my membership. My reason for doing that (and the reason I'm not naming the club) is because it was taken over by another well known book club, and I didn't like their policies.
What I never liked about book clubs was the way they were run. They would either send you a book and you had to send it back if you didn't want it, or they would send you a notice that they were sending you a book, and you had a certain amount of time to tell them you didn't want it. After that, they sent the book automatically and charged you for it. (This was the reason I quit my book club. I had--years ago--fulfilled my introductory obligation and had requested that I move into a program where I simply perused their catalog and bought when I wanted to without any monthly reminders or obligations. Staying with the new company was going to throw me right back into that old program, or at least something similar, and I just couldn't see why I would want to do that again).
On the other hand, belonging to a book club enabled me to find books I might have never been exposed to otherwise. The books were carefully chosen, and that's how I found the author Fredrik Backman (I posted about a book by him a few weeks ago).
In its heyday, there were a number of book clubs, including specialty clubs for crafts, history and religion, and many of those book clubs still exist, although, as in many other areas, companies have consolidated until many of them (maybe even most) are owned by the same company.
Many of them have become irrelevant. With the advent of online shopping as well as ebooks, buying books has never been easier, and most of the online stores are less expensive than the book clubs can afford to be. Moreover, with the consolidation of clubs and employees, things don't always run as smoothly as one would like (I'll forgo my most recent complaint. Suffice it to say that errors were made and never corrected).
Still, I'm going to miss belonging to a book club and having those hand-picked choices delivered to my inbox. It feels like the end of an era.