[Snild]

There are some downsides.

https://github.com/libexpat/libexpat/pull/789/commits is a PR of 16 related commits. Many of them make sense individually, but are depended on by subsequent commits.

Reviewing them separately makes sense. It's easier on the reviewer (and future readers) to handle multiple smaller changes, especially since each is more tightly coupled to a rationale in the commit message. Unfortunately, github's PR-focused UI doesn't really make this per-commit review as convenient as Gerrit does.

Additionally, the last two commits are authored by another contributor. This metadata would be lost in a squash.

Of course, each intermediate commit must build and pass tests. WIP and cleanup commits are squashed locally before final review/merge.

You could argue that all of these could be separate PRs, but I think there's value in grouping them up with that final merge commit, showing what one was trying to do at a larger scale.