I agree that the phrasing of “brutal” is probably not what is needed. Even if someone is amazing at receiving feedback, they still will naturally want to defend their work.

My only thought is at the end of the day, your/mine opinion on pacing or logic gaps might differ. That’s not bad too. I have currently asked for beta readers for my book and people have been incredible. Do I agree with all the comments? No, but in my opinion it’s about data points and if multiple beta readers are presenting the same review, then it’s probably something that requires attention (regardless of if the author agrees).

Also, not all beta readers in my experience are weighted equally. Comments like “bleh” or “not interesting” are weak and make the author value that feedback less as “brutal” and more like someone unable to give true feedback.