The argument made to me by a coworker (for why we should squish + rebase all PRs before merging) was that it makes it easier to use `git bisect` -- which is basically a binary search for Where a Bug was Added.

In practice, I've never done this. I think it's that I work on a smaller codebase, or that I am 1/3 to 1/2 of the developers, and so it nearly always has seemed easier to read the code + tests, and poke at values in a debugger, than to use binary bug search. If I were on a larger team, or a larger project, `git bisect` might be more useful.