> The post compares an Apple 2e, which is a single-tasking OS that just displays the pressed key in the basic interpreter on the screen, and modern devices, where it is not always clear, what kind of app or setup is being used. But we know, that it's plenty of layers of GUI and OS code, that most people don't want to miss. Not to mention, that mot of the higher input lag is not detectable by humans in normal work conditions.

You can do an experiment for yourself along these lines. A few years ago, I pulled out an old laptop that had Gnome 2.x installed as part of an Ubuntu release from circa 2009. In every respect, the hardware from this machine (which itself had been a budget laptop when it was purchased in 2006) was worse than the hardware I was using in my daily life. I was struck (almost startled), however, by the difference in how immediately it responded to my input compared to my daily driver at the time—to the point that it distracted me from the original reason I booted it up in the first place.

A system capable of running Gnome 2.x is no pre-Mac, pre-multitasking system. In fact, it has all the capabilities/affordances that you'd expect and need from systems today. So your characterization is less than kosher (basically a motte-and-bailey).