Microsoft has been having similar font rendering issues for years, so I guess Apple felt left out of this club. They spent all this awesome work & research creating ClearType and then when Vista(?) happened they suddenly decided screw everything, let's switch back to grayscale antialiasing for no reason... now everything on the taskbar (or seemingly anything DWM-rendered) is grayscale-smoothed, which makes me want to tear my eyes out.
> let's switch back to grayscale antialiasing for no reason...
The actual reason is that switching to hardware-accelerated font compositing means that you lose out on subpixel antialiasing, because of complications related to blending. The classic way of doing subpixel text rendering means you need three distinct alpha channels, and most hardware only lets you supply just one. There are ways of hacking around this with dual-source blending, but such a feature was not supported at the time of Vista. In Windows 8 and up, DirectWrite can now support hardware-accelerated subpixel AA, and the OS does so by default.
> The actual reason is that switching to hardware-accelerated font compositing means that you lose out on subpixel antialiasing
But what was this crazy obsession with hardware-acceleration of every rendered character and its grandmother? While you're busy Flippin' 3D I get it, you can temporarily render aliased Wingdings if that makes your life easier, but at least for Pete's sake I just want to enjoy not tearing my eyes out the other 99.99999% of the time. If there was anything slow or poorly implemented in XP it honestly wasn't the taskbar font rendering.
(Not angry at you; just annoyed at the situation they caused.)
> DirectWrite can now support hardware-accelerated subpixel AA, and the OS does so by default.
I can't substantiate my comment with academic sources, but here's my memory from the past decade: the people designing interface guidelines for mobile operating systems decided that carefully designing static visual assets for UIs was a waste of time (with similar technical complexity reasonings due to the number of different display resolutions/pixels per inch/aspect ratios)
Market context: Microsoft yearned to implement the Metro UI they'd been researching for a long time (Zune was its public appearance) — and Vista kind of soured people on Aero by osmosis; third-party Android applications always had consistency issues, so Google wanted to mandate something that would be generic enough to work (and be easily implemented) for all apps but also look distinctly specific to Android; Apple wanted to signal some shift to upscale high fashion (parallel to "everything is black glossy glass and aluminum" in its industrial design) and understood fashion-minded upscale as a mix of modernist typography with neon bright contemporary color schemes.
To make up for the boring visual aesthetic that often resulted, they recommended adding animations throughout apps. Most of these animations aren't very helpful, but they keep the user distracted for a moment.
I chose my words carefully: font compositing, not rendering. Font rendering still happens in software, but in order to composite it correctly into the surface requires DSB. I (hopefully) shouldn't have to explain the advantages of using hardware acceleration for app rendering in general.
I'm aware of Slug (and other GPU font rendering techniques). Slug, however, doesn't have subpixel AA (it doesn't make sense for it to, since its main goal is fitting in a 3D scene), and requires a moderately expensive (read: hard to do realtime) up-front bake process which converts the font into a pair of textures.
> then when Vista(?) happened they suddenly decided screw everything
What? ClearType was basically introduced in Vista and refined in Win 7.
Win 8 is when they start to remove it for various applications (UWP, and some others) due to its poor performance on retatable devices (tablets mainly).
