reviews don't really fit under the QA model that SE sites follow
You're absolutely right, and that's why these reviews are being published on an off-site blog instead of on the Q&A site.
Literature SE is a Q&A site, but it's also a community of people interested in literature, and there are a lot of things such a community might want to do which don't strictly fit into SE's Q&A model. For example:
- Discussion of scope, best practices, etc. We have meta for that.
- Idle chatter between community members getting to know each other. We have chat for that.
- Promotion of our site and its best posts elsewhere. We have Twitter for that. (Back in the day, every new SE site was given an associated Twitter account. So older sites still have them, but newer sites like this one need to create their own - unofficial, community-maintained - Twitter accounts.)
- Reviews of things the community might be interested in (works of literature, in our case). Again, back in the day every new SE site was given an associated blog, hosted by SE but contributed to by the community. The official SE blogs were shut down a couple of years ago, but some sites created their own - again, unofficial and community-maintained.
That's pretty much what happened here. Since SE no longer provides the platform for what used to be an official thing on every site, Literature SE's community stepped up to make it themselves. Reviews are absolutely not on-topic for the main site, but they're something our members might appreciate or want to take part in, so we have a separate side site for them.