Plus the author doesn't even seem to do this himself, his reading list is roughly 30 books on the same topic of pop "productivity" and selling the dream of having a successful business career.
There are certainly singular books that have changed me, but I never went into them knowing the impact they'd have ahead of time -- how could I? In my reading habits I always try to be curious, open, and meandering. "Productivity" is for boring people.
No matter how you spin it, it's a feel good line. It's a line that cannot even work in theory, as you cannot know the book changes your life prior to reading it.
That said, I agree with you that having more sources of information reduces the risk of falling to the misconceptions of one or a few authors.
Book reviews and ratings saves you time by helping you avoid the bad ones to begin with. In that case good star reviews does matter. The reviews helps you avoid those books that you mention in your example.
Though I agree that reading widely does help, it makes sense to focus your limited time to read and use sources that have been thoroughly reviewed by other people
This is just flat out wrong for non-fiction. This is not a good way to use books or any research material, except perhaps meta-analysis’ but even then with caution.
It doesn’t matter how many 5 star reviews it has, or who wrote it. You will be far better served by reading many writers on the topic and using your learning from each to compare and contrast between the materials and arrive at a deeper understanding.
For example, there are thousands of books with a theme that could be written as “how i got rich”. Every single one of these books tells the version of the story the author would like you to believe rather than the actual truth because the simple fact is the author themselves, despite living that life, may not actually know the truth of the matter themselves. Plus some actively seek to deceive.