You're not daft for being colour blind, or daft if you physically cannot see it.
Have you read the link? It shows how people without biological limitations on their colour perception cannot perceive colours. They're not biologically colour blind, but just can't notice the difference between blue and green. And the blue thing you can blame on them being colour blind, but the green thing is
us being blind to colours that are obvious to the Himdi. That's not because we are biologically blind to green, but we just haven't learnt to perceive them the same way.
But if you want to just compare frame rates - you should ask your friend if he can see the differences here:
https://www.testufo.com
That's a test contrived to showcase the differences. We're talking about games here, and you're calling someone who can see 60 fps in games but can't really notice a difference between 60 fps and 30 fps daft. I stressed to him, "can you not see the difference?!" and he was like, "I guess it's a bit smoother maybe." Unlike you and me who see 60 fps and perceive it as much better, he didn't, and it's not because he's mentally deficient.
This is like calling a blind person daft for being unable to see, or someone legally blind for being unable to see something so obviously in-front of your face.
No because those people can't see, rather than can't perceive. It would instead be more like you and your Significant Other looking at this colour chart:
And your SO saying they only really liked 3, and you forgetting and at the store, grabbing 7 because they all look the same, painting the wall, and then your SO calling you daft for using the wrong colour.
It's not necessarily a fair test to your friend to look at 2 frame rates, 2 resolutions and declare a winner without isolating where to look and what to look for, and then assume he can't see it either. 30fps and 60fps look pretty close pixel movement to 240pixels per second.
This entire thread is about exactly that though! Given a game with a choice between resolution, quality, and framerate settings, which would you prefer? In this case, a choice between higher fidelity (which some people will say they can't notice - that doesn't make them daft) and higher framerate (which some people will say they can't notice - that doesn't make them daft), he chose resolution because it was immediately a better quality experience
for him and I chose higher framerate because it was immediately a better quality experience
for me. Neither of us is mentally deficient for our brains valuing a different aspect to the moving image rendition.
Indeed, that side-by-side in isolation comparison has the same result for every rendering aspect.
"Here's GTAV at 240p, 480p and 1080p - which do you prefer?"
"Here's GTAV with flat lighting+no shadows, flat lighting+shadows, and GI + shadows - which do you prefer?"
Everyone can see everything when shown in a white, silent room with just two or three variations to look at.
Your statement and argument seems to be trying to deal with human perception as if it's a string of mechanical and logistical operations. It's far more complicated than that and you shouldn't assume that what you perceive (not see) is the same as everyone else.