> You can’t merge partially merge a large “review commit by commit” PR so you are forced to wait until it is all ready to merge.

These are two different use cases. I thought we were talking about the one where a set of changes is more readable commit by commit but you still want to merge the whole set of changes, not the one where the change is too big to review and merge at once so you have to break it up into multiple reviews. The latter use case is more rare—frankly, it’s a bit of a red flag otherwise—and wasn’t difficult anyway.

Microsoft didn’t need to build anything because it was already built into Git. The only problem is, if people knew how to use Git, Microsoft couldn’t lock them into a proprietary version control platform.