Why would you want to restrict yourself to a one-dimensional mentality of commits when the source control system handles two-dimensions naturally and well? It seems to me a bit like wanting to only use about half the tools that you have available.

Squashes and Rebases delete information entirely out of source control. If a PR adds 100 lines of code, then deletes 50 of them and you squash it, you've lost 50 lines of code. Once your PR tool garbage collects those original commits you can't easily get it back. Maybe that's fine and that was garbage code anyway, but it was part of the process of getting those 50 lines you kept and could be relevant to questions of "why were these 50 lines added?" Were those other 50 lines alternatives that were rejected in testing, perhaps? Worse, were they deleted on accident in a bad inner merge and not caught in time?

I feel a lot less confident in the YAGNI code tossing that Squashes and Rebases do. I've had too many times where I've needed to code dive a fix out of a Merge commit or out of a long winding PR that went through several alternatives.

Git provides some great 2D navigation tools such as `--first-parent`. You can have "I just want a view of PR merges" and the structure of "the commits below that PR are accessible, too". I can't see why you wouldn't want that. That's what source control is for, "save all the minutia in case I need to find it again someday" and it is just a UI problem if you don't want the 2D view by default.

I think the "subway diagrams" that most git UIs show look pretty, especially in screenshots, but are not the UI most people actually want to work with day-to-day. I think a lot fewer people would be so adamant about squash-only or rebase-only workflows if more git UIs took a "1D" first view of the git DAG instead of "subway views". I think more git UIs should start with `--first-parent` and provide drilldown into "lower" commits instead.