There are roughly spoken two different approaches available how to create pdf files: Scribus vs. LaTeX. Scribus is graphical oriented while latex is text oriented. To answer which one is better whe have to take a closer look into a working directory. Suppose the idea is to create a book. Then the working directory contains of some files for the graphics, a single text file and more graphics file in a vector format.
It is very likely that the file size is very different. The text file has maybe a size of 500 kb while the graphics file have combined around 20 MB. According to the size the graphics files are more important because they are bigger. And here is the problem, graphics oriented layout software puts a high priorioty towards the graphics file. The idea is these files are handled first. While the text file which has only 500 kb is treated with low priority. The idea is that nobody cares what is written in the text but the audience is interested only in the graphics.
At least this is the assumption behind the scribus software. The problem is that in the reality it is the other way around. Creating a 500 kb large text file takes a long time. A trained author will need weeks or months until he has written such a document. In contrast, creating vector graphics and especially photos with a camera will take only hours or minutes.
Let us take a look how LaTeX is seeing the world. LaTeX assumes that the most interesting content is located in the text file. The text file is rendered into a pdf document and in the first run the draft mode is activated. Taht means the images are not visible but only the text. This allows to proof read the text and new sections. LaTeX is not the only software which has a focus on text. For example the markdown format or the MS-Word software have a similar approach. In all these cases the idea is that graphics are an add on to the text but not the other way around. That means, text without images makes sense, but images without text not.
This understanding is not only a subjective measurement but it has to do how long does it take to create a certain sort of content. Suppose somebody is using a photo camera and is making some photos on a single day. How many content can this person produce? Very large amount of information. He is able to create 500 photos each one has 3 MB so it is 1500 MB in total. In contrast it is not possible to create on a single day a plain text file which has this size. The reason is that the typing speed is much smaller. And proofreading a text takes longer than applying a filter to a photo.
The initial question was which sort of software is great for creating books. The answer is that it should be a text oriented software in which graphics can't be displayed or are handled with a low priority.