Just to be clear, your premise of "give me" is flawed because not every "commit" was meant as a capital "C" Commit-a-Logical-Unit-of-Work. Instead, many commits in private local history are a more mundane commit-as-a-backup-checkpoint-savepoint. The "savepoints" are like "^H Backspace". Asking "why the programmer gave you those particular savepoints" is like asking "why did he gave you those ^H Backspace keystrokes". It's a nonsensical question.
The confusion is that the same "git commit" command is used for 2 very different semantic purposes:
(1) git commit -m "fixed bug #23984" --> as Logical-Unit-Work
(2) git commit -m "wip" --> as meaningless backup/savepoint like Ctrl+S save
The type (2) was for the programmer's internal purposes of safety backups, cleaning up whitespace, typos in comments, reflexive muscle memory of saving often, etc. They have no semantic meaning to "give you". Type (2) commits can have deliberate broken syntax and they're not meant to be built or be bisected.
Type (2) commits should never be discouraged because saving work often (including broken midstream work) is a good habit but from an outsiders perspective of the reviewers upstream, they are way too noisy. The spurious commits could be less than 30 seconds apart with no compile/build step in between.
Linus Torvalds has described his thoughts on rebasing:
http://torvalds-family.blogspot.com.au/2009/06/happiness-is-...
From a strategic standpoint, thinking of that data as anything other than 'destroyed' would be a grave error of judgement. From a retention standpoint the difference between 'could' and 'did' is profound.
That's an issue with GitHub itself, not an issue with the method of squashing commits before merging into master. See gerrit as a prime example of separating reviewing code and your master branch.
A commit to git is a named snapshot of a file tree. That's it. All the other "worthiness" we ascribe to a commit is communal. A person's unhygienic work-in-progress can give you insight into their thought process or their work ethic. Why did this person give me this particular named snapshot of their file tree? I expect they are tell me (or future them) something and I can respect that artifact and preserve it, just as easily as you might angrily suffer from it and destroy it.
CI or "git bisect" "worthy" are orthogonal considerations and also vary between communities and needs.
If there is something we can agree on here: yes, all commits are not created equal. Even all commits aren't worth preserving equally. That said, I think there are tooling solutions here far beyond "destroy that what you dislike".