While reading Dave’s riffing on his perceived lack of apps, particularly good editors, I am wondering whether he has spent any time looking at the iOS or Android app stores. It seems to me he is only looking for desktop apps, and my sense is that much development as moved from the desktop to iOS. Cynically, I think development much more about making money today that it might have been back in the day.
My suggestion to Dave would be to do a search on markdown editors.