There seems to be a confusion. The stacked diff workflow mentioned here is just a way of sequencing a feature development by breaking it up into smaller submissions/PRs (for review and merge). The goal here is to reduce the time spent waiting for reviews and approval. This is similar to how processors achieve more throughput through pipelining (in terms of instruction scheduling). Here the 'stacking' they refer to is the stacking of feature branches.

I believe what you are referring to is the treatment of a change set as a stack of patches, using tools like quilt or stacked-git. The patch stack can be manipulated like pushing and popping patches off the stack, and merging changes in the working copy to the patch on top of the stack (called refreshing).