This, basically. And for probably 80% of issues, a maintainer might actually read the notification, but to click through, leave some sort of intelligent / hones

This, basically. And for probably 80% of issues, a maintainer might actually read the notification, but to click through, leave some sort of intelligent / honest reply, and either click close or reply and move on takes infinitely more time (when you're dealing with 100+ new issues and PRs a day) than not responding and moving to the next one. A non-response does signal one thing—the maintainer doesn't seem interested enough to touch the issue. Fork the project or maintain a patch separately if you need to, and move on.