I often use the old trick of skipping to the end to see if there is a coherent conclusion, and if I think the conclusion is interesting, I’ll go back and pick my way through the body of the article.
I agree with your points though in general. I think this is even worse with many non-fiction books. So much fluff when the main points could be summarized in 10 pages.
The worst fluff I think is from analogies/anecdotes that get spaced out because the author wants you to feel what it's like or something like that. I'm sure some readers really appreciate it, but when the author doesn't tell me what I should be looking for beforehand, I just don't have the patience.
I agree with your points though in general. I think this is even worse with many non-fiction books. So much fluff when the main points could be summarized in 10 pages.