> Linux seems to be doing just fine.

"just fine" is not what we aim for. "just fine" is probably what they thought of the OpenSSL library before heartbleed.

> Accepting drive-by patches carries an enormous cost. It’s very common to need to rewrite them substantially.

Sure but it sounds like you're making a generalization about a specific instance you know nothing about. There doesn't seem to be an enormous cost detailed by the maintainer in the email thread. Just that he'd rather gatekeep the project and rob someone of the opportunity for contribution.