Email chains and mailing lists are not really a practical way to develop anymore, and it is increasingly anachronistic

By what objective measure? Just because everyone listened to Github’s siren song, doesn’t make it so.

So many Open Source projects are just one or two maintainers. So many PR’s on Github involve just two people. That would all work over E-Mail, which is by design decentralized, unlike the web, which is by design not.

This was always baked into basic git from the beginning if you review your code in E-Mail chains or mailing lists.