Hey, we're in my territory!
Something to note is this premise is disputed by A LOT of experts in this domain. They've been challenged to a debate on this by Marc Effron (not my favorite guy but does generally have grounded thinking in his work) with proceeds benefiting charity but no uptake yet. They have also not shared their data in a way that enables replication or outside validation (or hadn't lest I checked). They is a pretty robust history of peer-reviewed research that doesn't come to the same conclusion.
I think they are on to something here but I think they are taking too far. For their "Source of Truth" section, most of what they say is true, particularly about rating and assessment of employees. Extending that to say suggestions on future behavior from others is also value-less is wrong. The former is problematic because it's treated as a source of objective truth that personnel decisions are made against, the latter is clearly a single subjective data point people can reflect on and potentially integrate into future behavior.
For "How We Learn" section, much of the words written are true but the conclusion goes beyond what I have seen data justify. Yes, we get better faster at the things we're already better at. Should that mean focusing on strengths is often a better coaching direction than weaknesses, yes. Does that mean we shouldn't do the latter or that it is value-less? No. It does mean we have to find ways to make weakness-oriented feedback happen in a repeatably non-threatening way.
On the "Excellence" section I'm again in agreement with most of it, but have fewer overall critiques. I should think more about this. I still say the conclusions are not natural endpoints for the points he makes.
Then, interestingly there is a table near the bottom. I find it interesting that many of those things you should "Try" rather than "Instead of" are indeed types of feedback and modern organizational development professionals espouse. Language really does matter, that's a great table with great suggestions, and most of those are feedback prompts.
All that said, I truly like Marcus Buckingham and find his work to typically be evidence-based (to the extent work like this can be) and on solid ground. Here is a brief video of him that is on a related topic that I think everyone should really take to heart if interested in this topic. https://www.marcusbuckingham.com/rwtb/performance-management...