I think you have some good truths in your post, but I also think they're rendered somewhat irrelevant by the fact that a "diff review" is, in my repeated and frequent experience, simply incomprehensible. I can't do any review with an incomprehensible mass of red and green lines interspersed with each other. It's not a useful view of the code, or at least not a useful primary view.

I push through and do it anyhow, because this is one of those "they're not paying me to have an endless party" sort of things. But I completely 100% agree with the author that it is not a very useful view.