WhisperingWind Apple disabled subpixel font smoothing (also known as subpixel anti-aliasing) starting with macOS Mojave, which was released in 2018. The company shifted to grayscale font smoothing instead. This change was made in part because subpixel rendering is less effective on modern high-resolution Retina displays, which have a much higher pixel density compared to older screens.
I read about this when Mojave was released. I also noticed firsthand that text was much harder to read on standard-DPI monitors starting with Mojave, with one of the worst scenarios being trying to read a PDF document in Safari (could have been a Safari issue in theory). Going beyond my previous point (and I'm not sure where this started or if it was always the case), macOS text on standard-DPI monitors seems categorically fuzzy, and I've seen examples within Apple's own app UIs making me suspect that macOS text rendering has no concept of physical pixel geometry. I frequently saw single-pixel-wide text elements (for example, for the letters 'j,' 'i,' etc.) seemingly sitting between two pixels, such that two pixel columns were at 50% instead of a single pixel column at 100%. The default Terminal font and size was awfully blurry for this reason and I had to increase the size (they also got rid of the ability to disable antialiasing in the Terminal in Monterey or maybe earlier, before restoring it in Ventura). The Time Machine preference pane in Monterey also had horribly blurry text for the "Back Up Automatically" (IIRC) text, to cite another specific example.
As you pointed out, this is inconsequential on high-DPI screens. However, if I am correct about macOS pixel geometry unawareness for text rendering, then the macOS blurry text issue on standard-DPI screens goes beyond subpixel versus grayscale antialiasing methods.
When choosing a HiDPI monitor, this problem is resolved.
For this reason, when I upgraded to an Apple silicon MacBook Pro I tried practically every available high-DPI 1080p external monitor (LG 24UD58-B, LG 24MD4KL-B, and Dell P2415Q), and all were uncomfortable (this was prior to StillColor, so quite possibly the aggressive Apple silicon temporal dithering was to blame). The built-in MacBook display was equally or more horrible on the mini-LED 14-inch MacBook Pro, and was where all my vision problems started. I ultimately reverted to an Intel Mac with a standard-DPI screen, but my vision was never the same after that.