That isn't the normal use case for commit squashing though. Generally, trunk/master/main isn't ever rewritten. Squashing is usually done on feature branches _before_ merging. What does that look like in fossil?
It seems like part of the problem is that fossil is designed for a very different workflow. See https://www.fossil-scm.org/home/doc/trunk/www/fossil-v-git.w.... The autosync, don't commit until it is ready to be merged workflow might work well for a small flat organization, but I'm not sure how that scales to large organizations that have different privilege levels, formal review requirements, and hundreds or thousands of contributors.
In terms of Git and the usual commercial SCM practices, I'm speaking empirically. Everywhere I worked in a team, leaders and managers wanted main branch's history to be a bird's-eye view, to have every commit fully build in CI/CD, and be able to find who introduced a problem (admittedly this requires a little more digging compared to Fossil, though). Squashed commits help when auditing for production breakages, and apparently also helps managers do release management (as well as billing customers sometimes).
Do I have all sorts of minor commits in my own projects? Sure! I actually pondered using fossil for them but alas, learning new tools just never gets enough priority due to busy life. I'd love to learn and use it one day. I'm sick of Git.
But I don't think your analogy with a photoshopped / retouched picture is fair. Squashing PRs into a single commit is not done for aesthetic reasons or for deliberately disappearing information -- a link to the original PR with its branch and all commits in it remain and can be fully audited after all. No information actually disappeared.
I believe a better analogy would be with someone who prefers to have one big photo album that contains smaller albums which in turn contain actual photos of separate life events that are mostly (but not exactly) in chronological order -- as opposed to Fossil's approach which can be likened to a classic big photo album with all semantically unrelated photos put in strict chronological order.
I'll reiterate that my observations and opinions are mostly empirical. And let me say that I don't like Git at all. But the practice I described does help in a classic team of programmers and managers.
I concede that Git and its quirks represent a local maxima that absolutely can be improved upon, but at least to me the jury is still out on what's the better approach -- and I'm not sure a flat history is it.
I frequently use git rebase in interactive mode to rearrange and curate my commits to form whatever narrative I'm aiming for. Commits are semi-independent stories which can be merged, in order, at any rate and still make sense. Each commit makes sense with respect to history, but doesn't care about the future.
I squash and rearrange and fixup commits until they look they way I want, and would want to see if I was looking at a history, and then send them for review.
Whether you merge my branches, or fast-forward and rebase the individual patches, makes little difference to me. But please don't squash my hard work.
Not looking to pick a fight here, mind you, but the Linux kernel is hardly a representative demonstration oh how to consume Git out there in the wild.
The way you describe your usage it already seems you kinda sorta do your own squashed commits, only you want several of them get merged into the main branch, not just one. So you're still rewriting history a bit, no?
The problem with squashing at review time is that it is incompatible with my model. I'd rather teach engineers to not push shitty "fix the thing" or "oops" commits that are ultimately useless for me, the reviewer or reader. Just use git commit --fixup and git rebase --autosquash as $DEITY intended and force push away. It's your world, you'll be deleting the branch after you land it anyways.
The tool works so well when used as intended: a distributed version control system. The centralized model adds so much pain and suffering.
The difference is that Fossil does not promote the use of commit-squashing. While it can be done, it takes a little work and knowledge of the system. Consider the premature-merge problem in which a feature branch is merged into trunk before it is ready, and subsequent typo fixes need to be added. To do this in Fossil you first move the errant merge onto a new branch (accomplished by adding a tag to the merge check-in) then fix the typo on the original feature branch, then merge again. So in Fossil it is a multi-step process. Fossil does not have a "rebase" command to do all that in one convenient step. Also, Fossil preserves the original errant check-in on the error branch, rather than just "disappearing" the check-in as Git tends to do.
The difference here is a question of priorities. What is more important to you, an accurate history or a clean history that tells a story? Fossil prioritizes truth over beauty. If you prefer a retouched or "photoshopped" history over an auditable record of what really happened, Fossil might not be the right choice for you.
To put it another way, Fossil can squash commits, but another system might work better for you if commit-squashing is your go-to method of dealing with configuration management problems.