Seeing this near the top of HN is a bit like seeing a "Why Does Italian Have All These Screwy Verb Endings?" post near the top of a web forum for professional students of linguistics ...
What's obvious to you might not be obvious to everyone. I've only heard reference to the issue previously but never looked at a detailed discussion, mostly out of not caring because I've never had to do something that depended on detecting keyup events in Linux in a non-browser context.
Really? There is almost no information in this article that I have ever heard before, and I imagine that I'm a pretty typical reader of this forum. You might have have a very mis-calibrated model of HN readers.