Correct me if I'm wrong, but I think font hinting isn't needed for high DPI displays? I believe macOS Mojave removed subpixel anti-aliasing because Apple doesn't ship anything but high DPI displays anymore.
Font hinting is still used, as the native resolution of most TTFs is 2048 upem so even at 72pt you’d need a 2048 dpi display to perfectly render a glyph.
You’re right that sub-pixel (color) antialiasing has been removed from macOS but regular grayscale antialiasing, and hinting, remain.
"Needed" is subjective. Libschrift[1] is an example of a TTF renderer that doesn't do any. I translated Libscrift to Ruby[2], and I considered whether to add support for it, and decided it wasn't worth it for my use (it's now the font-renderer for my terminal, and by extension my editor) despite only using it on 1920x1080 on a 27" monitor.
My reasoning for not bothering was much what you suggest - if it's acceptable to me now on a resolution that low, I'm not sure I see the point in supporting even worse conditions given how cheap 4K displays are. The need for hinting is only going to go down.
Maybe one day, but I'll note e.g. FreeType also did a lot of work on auto-hinting because as it turns out the hinting in a lot of TTF files is pure garbage.
That might well be the original motivation, but note e.g. ttfautohint development 2011 or so onwards [1] intended to strip hinting programs and replace them with the output of the autohinter because so many fonts have awful hints.
[1] Not sure exactly when the ttfautohint work started, but both Microsoft and Google donated money to it in 2011.
It’s true that autohinting is nowadays the norm but I’d be more generous to those old fonts as they were aggressively hinted for black-and-white rendering. It’s not until ClearType was enabled by default in Windows Vista c. 2007 that those old hints became undesirable.
> because Apple doesn't ship anything but high DPI displays anymore
People still connect their Apple computers to low-DPI monitors all the time. High-DPI monitors are still a rarity. There's the LG UltraFine, the Studio Display (too expensive for what it is), the Pro Display XDR (the $1000 stand lmao), and that's really it.
I'm writing this comment on a 2K monitor connected to a modern MacBook.
> People still connect their Apple computers to low-DPI monitors all the time.
They do, but the fonts are visibly blurry on those, as they did indeed remove the subpixel antialiasing. Thankfully, the Gtk4 developers removed it as well, so Linux (or at least the GNOME desktop) will soon look like crap as well.
