Comment by WorldMaker

Sure, but also no one particularly wants to CI every commit inside a PR, so there is a usefulness in `git bisect --first-parent` as the "first pass" of known CI points (merge commits presumably from PRs) to find the "PR that introduced the problem" and then drill down into every smaller commit to see if you can get additional bisect information (from commits that may or may not have passed CI in the first place in development work-in-progress).