They should not be a thing. At least not until there is already consistent active discussion threads happening for a given series. If I want to discuss a new chapter of something, and there isn't a post already, I will make one.
As it is now, the dozens and dozens of empty discussion posts only drown out the few posts by people who DO have something to say.
They also show up in my subscriptions as a wall of spam, and do the same for "all". One post is enough to facilitate discovery of the community, a dozen does the opposite.