I'm a random stranger on the internet, so with
no intent on telling you how to live or interact :), My own limited biased subjective 0.0005 cents:
1. Original question: "Who's still using this?" is direct and to the point; I grok it. But note that some people in many contexts may interpret it... aggressive. Human mind fills in detail in blunt / short sentences. Politeness in some cases is filling in those blanks pre-emptively. Uncharitable reading of your question would fill in the blanks in "Who's still using this?" as "WHO is still using this?" expanded to "WHO is still using this???" expanded to "WHO is stupid enough to still be using this???". They/We would be wrong, but be cognizant of good and bad interpretations of writing.
But that's very minor and extremely audience specific. Bigger point:
2. Charitable reading. This is such a hard thing to do for all of us, especially on the interwebs, especially when there's even a minor difference opinion. I thoroughly, genuinely, believe that the keyboard-shortcut poster provided best possible explanation and tried very heard to type it up and come up with meaningful analogy. I will totally steal it! :) When you read it / interpreted it as a rant / over-my-dead-body, I in turn did not feel you gave them a charitable reading, which subconsciously meant I did not give you a charitable reading either.
So what I think would've made it appear as a true effort to understand, would've been... making a true effort to understand - reading the keyboard shortcut post with a mindset of "what information can I gleam from this / what can I learn / which insight can I take from this". Which, FWIW, is an approach that I think is phenomenally useful in life, I'm actively working on myself, and am successful some small percentage of time :D
(again, not claiming some useful insight, but since you asked, my 100 Croatian Lipa :). All the best!