The author never reveals the reason why he or she didn't contribute to a mailing-list driven project.
You're only assuming that it's the difficulty of copy and pasting a patch into an e-mail and clicking send; no such thing is written in the blog.
People who are motivated to hack on a program will usually find a way to submit.
Only programmers who've never been employed balk at using e-mail. If someone won't send me a patch because they are afraid of e-mail, that tells me they've never accepted a meeting request or submitted a status report. What else do they find "too hard"? Testing the code?
In the abstract, there is no technical reason why mailing list workflows can't work. But technology is pretty path dependent. The projects you mention are all quite old in technology terms. Would they be using mailing list workflows if they were started today?
[edit: wording]