Yes, but with the correct info? That requires a ton of proofreading. There's a ton of blogs about points/miles stuff out there that are often quite wrong about this or that. It's the interactive nature of those that take feedback that corrects such errors. A book that doesn't go through an equivalent process would likely be filled with information that was just wrong (not out date, but always wrong).

And, no, it wouldn't have all the info in one place. No one person knows everything, so any book by one author would only have some of that information, not all of it.

Why don't you start with a list of topics you'd want covered, and see any one person thinks they could write thoroughly about all of those topics.

Yes, when I explain to people, they sometimes say "you should write a book", but I know how little I know about some things in this points/miles sphere, because I've concentrated on other things. For example, I've accumulated more miles than I currently need in all the major US-based airline programs, and so while I have a bit of understanding about transferable points programs, and I've been building up points in some of them, I've never really used them to date (other than to transfer to those same few US-based airline programs I already have other miles/points in). And since I have more miles than I need for quite a while, I'm not an expert on what to do when you're short on miles (but that's a very major concern to many other people).

But, btw, many of the ways I accumulated those miles (and hotel points) in the past no longer work, so I couldn't even explain to someone how to replicate my position today, even if that was all I wanted to do.