Have you looked at the desktop monitor market recently? There are still a lot of models that are not substantially higher PPI than what was normal 20 years ago. PCPartPicker currently shows 1333 monitors in-stock across the stores it tracks. Of those, only 216 have a vertical resolution of at least 2160 pixels (the height of a 4k display). Zero of those 4k monitors are smaller than 27", so none of them are getting close to 200 PPI.
On the low-PPI side of things, there are 255 models with a resolution of 2560x1440 and a diagonal size of at least 27". One standard size and resolution combination that was common over a decade ago still outnumbers the entirety of the high-PPI market segment.
If you look at the Steam Hardware Survey results, their statistics indicate an even worse situation, with over half of gaming users still stuck at 1920x1080.
If subpixel antialiasing made sense during the first decade after LCDs replaced CRT, then it still matters today.
