It just doesn't go in my head how so many people have trouble understanding why things like VSCode or Atom are popular.

They're sexy, they are powerful (extensions for everything), portable, and extremely easy to extend thanks to Javascript being pervasive. I don't know for certain but I'd also assume writing an Electron app is easier than writing a similar app in a lower level language.

Is it really that hard to grasp? Performance has to be perceptible by the average person for it to affect user base. I prefer WebStorm but I've had absolutely no issues using VSCode on my laptop - which feels even faster than WebStorm.