Wysiwyg kind of fell apart once we had to stop assuming everyone had an 800x600 or 1024x768 screen, because what you saw was no longer what others got.
Not entirely, in these RAD tools you also had flexible layout choices and obviously you could test it for various window sizes (although the maximum was the one supported by your graphics card). Too bad many chose the lazy way and just enforced fixed window size at 800x600.
Most of the internet still assumes you're using a 96 DPI monitor. Tho the rise of mobile phone has changed that it seems like the vast majority of the content consumed on mobile lends itself to being scaled to any DPI - eg.. movies, pictures, youtube ect.
