In terms of feature branches:
The individual engineer is free to do individual commits in their branch as they need to in order to keep track of their work. Before they submit a pull request, they should rebase and squash all of their commits into a single one that thoroughly describes everything in the feature that is being committed. When used in conjunction with tools like Phabricator, Arcanist, and commit templates, the workflow is very smooth.
When another team member goes to code review their pull request, rather than having to examine multiple individual commits there is only a single one to examine and comment on.
Master history:
Rather than cluttering up the mainline history with 'Did this', 'Did that', 'Merged: Did this', 'Merged: Did that', 'Reverted: Merged: Did this' etc, you get a series of commits that articulately describe what each commit was for. In the event you need to revert a feature because it breaks something, its much easier to revert that single commit than trying to hunt through all of the individual commits from an engineers feature branch. And in that case, if you revert one of the commits from the feature branch it could break something else.