This doesn't really effect the iPhone, but a lot of apps completely ignore your intended subpixel layout. Windows or X/Wayland can be set correctly, and many apps do handle that correctly, but many don't.
Many enable subpixel hinting when it is clearly disabled by the user. Want greyscale because your monitor fringes hard? Too bad. Want aliased because it is a low resolution display or you hate fuzzy fonts? Too bad.
Also, many apps do detect correctly, but only detect your primary monitor, not the monitor the window is on. Doesn't effect you if you're single monitor.
And to further shit on broken apps: there are apps that are already using DirectWrite on Windows, and are force overriding the correct (default) settings. Why?!?! You were so close!
And to shit on the Internet as a whole: people screenshotting text for their websites that have Vista-era Cleartype tuning clearly in it. Isn't so bad on RGB monitors, but almost unreadable on BGR or any V orientation.
And one last insult: DirectWrite and Freetype only support RGB, BGR, VRGB, and VBGR. There are many other weird ass configurations, such as LG C2s having RGBW (which causes extreme haloing on text), and another OLED panel (forgetting which monitor) has RBG (why?!).
So screw it. I won't use non-RGB monitors until we live in a world we're doing 300% DPI equivalent (ie, 5760x3240 in a 24"; best I can get in a commodity is 4k in 24", or 200%), and I can't see the subpixels anymore no matter how much I squint.