When Crysis was released, people said they couldn't tell the difference between the highest settings and one step down (I don't remember the verbiage they used in game), and that may have been true. But today, with today's higher monitor resolutions and our more trained eyes, I bet many of us could tell the difference. Sometimes those settings aren't for today's hardware.
Another example was STALKER. It had an option labled something like "full realtime lighting". Enabling it tanked performance and appeared to have little image quality benefit. But, like the name suggests, the realtime lighting was done in realtime. So it had all of the benefits of realtime lighting. And those benefits weren't really appreciated back in the day, especially when you were comparing screenshots and not the game in motion and over a period of time. And to be fair, I think enabling this option made my computer generate screenshots. Single digit FPS if I remember it correctly. In some ways, I find analogies with this setting and current titles that have a huge performance hit with RT enabled. Maybe it's for the next generation of hardware.
