My point is that the LKML and what GitHub do is so different that the definition of “stacked diffs in general” can only describe a tiny aspect of each, if you want to call both of their approaches by the same name. From where I sit, the only common element between them is “they offer a way to keep discussion separated.”

If that’s all people are actually complaining about, there are a thousand better ways to “keep discussion separated” that don’t require me to pretend that it’s ok that only a subset of my branch is ok to merge.

In git, a branch is the thing you either merge or don’t. You merge multiple commits at once, or you don’t. It’s a great model. Breaking up the branch into smaller pieces, and giving people the impression it’s ok to merge the first commit but not the rest, just to unfuck the discussion UX, is putting the cart before the horse. I make a branch strictly because I want it to either all merge or none of it merge. It’s the only sensible approach in my book. If a discussion system is so bad that this is unworkable, it means the discussion system is bad, it doesn’t mean the conceptual model of a merge is bad.