The activity in this context isn’t just that you are reading, it’s that you have to interpret what is written into scenes in your imagination. This is also required when listening to books or podcasts. This is partly why they show much of the same benefits from reading are also gained from listening to books and kids being read to by their parents.
Fair enough; I shouldn’t have said “everyone” because that’s obviously not true, but only pedantically, for the most part. It’s not insensitive to say “everyone has a nose” and mean “except the very small percentage of people that don’t have noses due to birth defects, trauma, or genetics”.
1-3% of people have aphantasia. That’s not everyone, but it’s close.
Throughout my life, I thought "mind's eye" was a metaphor, and that people didn't actually see images in their heads. When I discovered aphantasia was a thing, and that I had it, I also accepted it was rare. But turns out, about a third of my male friends also have it. Not one female friend has it, though. It's a pity there isn't much research on the subject.
