I said elsewhere that the only use of squash that I strongly agree with is to remove bugs and other dumb mistakes.
What I disagree with strenuously, to the point of anger, is having a code as where every line of blame tells me only who made a change and what feature it was for. And I know too many people who think of every feature or pull request as a single commit.
THAT is lying, and I mean that in the judgement-passing definition of the word. You're fucking up the version history intentionally, and you should be stopped.
I'm not in the habit of reading code for fun. I have a job to do, and I want to do it. If I'm looking at the version history it's pretty much only for two reasons. Maybe I know for a fact there was a clever bit of code in this file and it's gone now, so I need to find it. Was it deleted or did you split isn't off into another file? I like those but they don't happen to me very often.
More often I'm reading blame because of a wtf moment. I can't think of a logical reason why the code looks the way it does, but I need to make a change and so I need to know if the person who wrote it was trying to do accomplish something or just confused.
Commit a8bcdef by dingus Implement feature #532
That tells me what changed, who changed it, how it changed and when, but I've lost the why. I know, you probably think "feature 532 is why, duh" but it doesn't tell the story of the intermediate states and why for instance they changed 'users > 1' to 'users >= 1'.
And if there is one class of commit should absolutely and under no circumstances ever ever be squashed it's any commit where you reformatted code. If a line changes and its part of a commit for a feature I'm going to assume that method body was all you, and stop looking. If you 'wrote' it but the commit message is "pretty print" I know I have to go pull a blame on the parent version to keep digging.