It's not about purity. It's about a workflow where everything lives in email rather than some company's walled garden. It also doesn't give a toss about newco

It's not about purity. It's about a workflow where everything lives in email rather than some company's walled garden. It also doesn't give a toss about newcomers. It's for users who want something very specific and know what that looks like already. It's like the same reasons that OpenBSD still uses CVS -- it works perfectly fine for those involved in the project and the switch to Git would not only take time away from what's important to work on but also add a ton of noise from new contributors who may not have the same goals as the project.