Then why deny it a harness it can also use in a human centric world?

There is no general purpose harness.

General intelligence not owning retinas.

Denying proper eyesight harness is like trying to construct speech-to-text model that makes transcripts from air pressure values measured 16k times per second, while human ear does frequency-power measurement and frequency binning due to it's physical construction.

Does this mean blind people are not intelligent?

Blind people do function within the context of a human-centric world, though, so they would qualify as intelligent.

Yes, but they use various "harnesses" to do so (dog guides, text to speech software, assistance of other humans when needed..). Why can't AI?

Assistance of other humans? You do realise we're talking about an intelligence test right, at that point what are you even testing for. I'm sure you've taken exams where you couldn't bring your own notes, use Google or get help from someone, even though real life doesn't have those constraints