There's a certain set of changes which are just easier to review as stacked independent commits.

Like, you can do a change that introduced a new API and one that updates all usages.

It's just easier to review those independently.

Or, you may have workflows where you have different versions of schemas and you always keep the old ones. Then you can do two commits (copy X to X+1; update X+1) where the change is obvious, rather than seeing a single diff which is just a huge new file.

I'm sure there's more cases. It's not super common but it is convenient.