We had this discussion already some time ago. There are three options for merging into master: merge commits, rebase merging, squash merging.
I think that with squash merging git suppresses the history of the branch that is merged into master. This feels a bit awkward (to me) since it might be useful to retrieve the history of that branch, in order to retrieve the thinking of the developer. However, I think that one can retrieve the branch from the successful pull request. So it would not be gone, but removed from view. (What happens if we ever move out of github is a different discussion.)
I am wondering if this might be a step in the direction of changelogs that Sebastian wants.
It would be easy: We would just switch on "enforce linear history" in the github settings.