So this is something I've noticed several times recently: recent anthologies often contain excerpts from novels.
The first time I noticed it was in some yearly collections of Nebula winners. The older collections of Hugo winners (I don't know whether the newer ones still do this) simply listed the winners in the novel category, and that was back when novels were never more two-hundred-odd pages due to limits of the publishing industry. Back then, you could probably have included the whole novel, but anthologies are collections of short fiction, so merely listing it made sense to me. With these Nebula collections, half the space in the volume was taken up with part of a novel, and I can't fathom what good that does anyone.
But at least with the Nebula anthologies you have the justification of "we're trying to represent all the Nebula winners but have a page limit," even if I think the solution is rather stupid. Since that time, I've seen the inclusion of novel excerpts in three other anthologies; all science fiction, all recent. I don't know if it's unique to science fiction, or if it started in another genre and moved into SF. It might actually make some sense in non-fiction, for example. A lot of my favorite non-fiction books have essentially thematic chapters (and in some cases some of those chapters were published as standalone magazine articles which later formed the basis for the book), so in those cases excerpts should work.
But fiction doesn't work like that; the novel form doesn't work like that. Chapters in fiction generally aren't thematically self-contained enough to be satisfying on their own; there's a narrative that builds throughout to a conclusion. So including excerpts from novels in SF anthologies is baffling to me. What good is part of a novel? Presumably you want me to like it, and if I read it and like it, I'll have to obtain a copy of the novel, at which point I'll have already read part of it out of order, which may make the first part of the book disappointing, since I've already read the exciting part.
Moreover, I usually read anthologies because I want to read self-contained, high-quality, short fiction; because I'm just browsing and don't feel like committing to more than an hour of reading one story. (The exception is single-author anthologies.) Often I don't even read the novellas in anthologies (or if I own them I read them much later than the short stories and novelettes). What's the point of including novel excerpts in multi-author fiction anthologies? I just don't get it.