Just from a logical perspective, there are countless people out there unaware of their own disabilities. Some might unknowingly be colorblind. Some might not even be aware that people can actually conjure images using their "mind's eye". This condition (of inability to imagine) is known as aphantasia.
It's actually a "relatively" common condition that affects 1 to 3% of the population. Most people who do have aphantasia probably aren't even aware of it themselves. From a logical standpoint, they'll just assume that "to imagine" is a metaphor.
Aphantasia is basically only ever seeing pure black when you close your eyes. Of course there are multiple degrees and or types of aphantasia. For example; some can imagine sound, some can dream (in images), some only have a reduced degree of inner visualization.
This chapter might've been somewhat enlightening for a few of you, but just remember; aphantasia isn't necessarily a bad thing. If you lose one thing, you'll gain another.