I recently came across a particular GUI quirk in a Linux distro, which went against my experience with similar UIs in Windows, Mac and Chrome. There were existing bug reports for it, attributing the cause to upstream. Upstream project said they were following the GNOME guidelines.
Eventually, I found the bug report that was filed against the guideline itself. The person who wrote that part of the guideline had responded that he made the decision based on a poll (presumably of people in the mailing list), and that no-one really had a strong opinion on it. He asserted that it was no big deal, and refused to reconsider the guideline.
Now, I think it is perfectly OK to make the wrong decision when it comes to something outside your expertise. If you are a backend software expert, it is OK for you to do the wrong thing when it comes to the UI for a project you are supporting for free. But when someone who does know that field makes a reasoned suggestion, you should not really be doubling down.
A UI/UX designer in this situation is not exactly going to be prepared fork and maintain a whole stack over this. It just means that the experience will be worse for users.