[swift]

On some of the projects I've worked on, although I can easily run a subset of the tests as a sanity check, the full test suite takes hours to run and has to be run on several different platforms because there is a lot of platform-specific code. There's no way I or anyone else can have confidence in any substantial change until it's run through CI. This is a cycle that may repeat many, many times in some cases before some obscure, platform-specific bug can be tracked down. All of those intermediate attempts would quickly totally drown out the signal in the commit history. This is just one of many reasons why for larger projects, rewriting history is really the only practical option.