The author appears to highly appreciate being able to contribute without an account, just an email.

I didn't quite get why that is. Isn't an account effectively just an email, with an additional password?

An account would be tied to a users table record as well as a profile, activity log, etc. Git is decentralized but source forges on average are not. I can make a commit to your code if you share the repo, but committing that code under my git user/email doesnt create an account on the source forge.