@Steve Knox, Buzzword and any other dingnuts out there.
Too. Much. Stupid.
ClearType has NOTHING to do with rendering PNGs. It has everything to do with rendering (wait for it...) type! Live type that is being rendered by the OS in an application. Not type that's already been flattened into a bitmap image like a PNG. The antialiasing on that text will have been done by whatever graphics software created the image in the first place. Since this is most likely to be Adobe's rendering engine (such as that in Photoshop), I can assure you the antialiasing routines do not match the output of ClearType on Windows or Quartz on OS X - this is a well-known issue that will cause most web designers in the world to start twitching if you mention it to them.
I have no idea what you think an "intelligent raster-based antialiasing routine" is but iOS has OpenGL, have you heard of it? Good luck using any other antialising method on a pixel-based display that isn't raster based. Good grief.
Your whole diversion into the order of RGB elements and subpixel antialiasing is just too La-La to even bother with.
The issue here is really simple, and quite frankly it's the author of the lousy article that's really at fault here. Instead of doing things properly, digital magazine publishers just dumped their publications out as a series of whole-page bitmaps (which incidentally often made each issue an eye-watering download) and now it's come to bite them on the ass because they were too short-sighted in their choice of publishing platform.
A higher-resolution display making lower-resolution images look crappy?
I'm shocked, SHOCKED I tell you.