> from the perspective of security, usability, and especially structured data transfer it's terrible.

Email is basically free, works well for up to 5 megabytes of data, and data security isn't much of an issue for open source work. The post suggests quite a few tools that improve the Git-email workflow, and I think some do prefer those to certain web-hosted Git interfaces.

> there's plenty of standard ways to transmit data that aren't SMTP

Are they free, federated, and as reliable as email? It may be inferior in some technical ways, but it's still a rational choice for small non-private data transfers, such as a Git patch or any another text.