Part of why it is bad practice in terms of research is that the marketing case for a book always asks how does this differ from other books in print. Writers may overlap previous writers, but they always have to have a different slice of material i.e. x author missed discussing points a, b, c or they have to have a different view, x looked at it from the point of view of business or entertainment. This means that some of the information you need is in one book, some of it in another book.
I often have very strong opinions about what I think, but I don't often express them directly. I like to write from more than one viewpoint because I would like people to realize that values place a big role in decision-making and we all have different values.
In the matter of reading I run into conflict with those who value success more than knowledge. I am unlikely to change. When someone buys an author's book, they do not buy their body, their mind, their heart, or their soul.
In this blog I write about books I have read because I know how hard it is to write. I love a good story. So much for success.