Well, as long as you use Hi-DPI (or "Retina", as Apple likes to call them) displays over your entire product line, subpixel rendering doesn't have as big of an impact anymore. I also suspect that's what's going on with the designers who are wont to disable subpixel rendering for their sites: they also mostly have Macs with Hi-DPI screens, so they don't see the benefit of subpixel rendering.
This goes out the window the moment you attach a second monitor for most folks. 1080p is very common; if we start talking about achieving retina at that resolution (say 220 DPI, a rough average across modern Macbooks), we're talking 10-inch displays. Even at 4k we're talking a max size of 19 inches or so before things get outside of Apple's ideal DPI.
I can't speak for you, but for my work and current eyeglass prescription, 27 inches is my starting point for comfort.
Even if I dislike it, Apple seems to have removed the global option to turn font smoothing off in Big Sur.
