It's not a matter of competence, it's a matter of effort. With github, most things are easily discoverable. With email workflow, you have to relearn a whole black boxed, badly documented custom workflow that you will get wrong several times.
When I spent 15 hours writing a high quality patch for free, I don't want to spend 5 hours more just to send it. I have a life.
I once was giving a training getting bored, so I timed how long it took for the dev to write down some simple tasks. The guys using vim and emacs were consistently slower than the guys with the IDE with GUIs.
I get that you can like vim and emacs better, and it's perfectly alright. But don't pretend it's more efficient. There are very few people (I meet one maybe each year) actually efficient with them because they are tools putting the burden of many tasks (reminding states, doing transitions, making very specific selections) on the user instead of the machine.
What language were you using? I wouldn't be too surprised about this if you were using Java or some other language with a lot of boilerplate but I'd be really surprised if this were true of python or a lisp: I'm pretty sure I can finish a simple script in vim in roughly the amount of time it takes to startup an IDE and start a new project. Also, were you letting people use their own vim setup or just a generic one?
When I spent 15 hours writing a high quality patch for free, I don't want to spend 5 hours more just to send it. I have a life.