It's tempting to see book recommendation questions open elsewhere on the site and say we should allow them here, but that way lies madness.
Questions don't automatically get closed: people who can close have to be made aware of them. Every site has questions that slip through the cracks, and just because you can find examples of questions that haven't been closed doesn't mean they're on-topic.
And that is just generally a good thing to keep in mind when it comes to other questions about whether something is off-topic: there are always going to be questions that prove or disprove the point.
There are a couple of good blog posts about the general guidance related to list and recommendation questions:
The takeaway from these posts is that questions need to teach someone something, not catalog opinions about something. So like many issues that are bound to come up, it's more nuanced than just banning or allowing all recommendation questions or list questions:
Before asking a question, we should consider not using "Recommend me a book about X", which isn't a very constructive question, and asking "What should I be focusing on when I'm learning about X?" or "How do I go about selecting resources for learning about X?"
Once the answers start coming in, do the answers actually provide useful information about why the recommendation is sound (ideally, a few paragraphs)? It's probably a good question that could be edited to make sure it doesn't become a honeypot for future bad answers.
Or are the answers merely a list of one line recommendations with no rationale for why one should look at it? Close the question as not constructive and start over, providing better guidance about what types of answers we're looking for here.
We should also take some cues from other sites on the network, and learning from their extended discussions about recommendation questions: