I think the "mind's eye" is also partly a "skill" thing.

I remember distinctly as a child doing a great deal of "work" developing my mind's eye. I didn't have TV at home, so I read a lot, and that necessitated me being able to take text on paper and make mind's-eye models of what the things on the page might actually look like (often without any visual references at all)...and I recall the early ones were definitely vague and fuzzy.

As I got older and did this more, and was exposed to more visual images of different things, my ability to visualize (and "hear") with detail got better, as with any skill.

I suspect folks who have the ability to use their mind's eye, but who haven't been pushed into (or interested in) developing it might not realize what a "trained" mind's eye can do because they haven't developed that skill.

But I do think there are some people with legit aphantasia who don't even have the weak, untrained mind's eye that most people start out with.

Sorry I'm well late replying to this! For some reason I didn't get the notification.

I've been trying really hard to boost my visualisation skills. The best I can do is a vague suggestion of an image, it's like made out of mist and dissipates instantly.

I think there's probably like you said, a lot of people who think not being able to conjure a distinct internal image = aphantasia. On the other hand, I'm pretty sure I'm aphantasic as I score extremely poorly on any tasks that require mental image projection (eg manipulation of 3D objects, spatial reasoning etc). Iirc last time I did an IQ test which broke down IQ into various regions, I scored 17% on that part. And there's practically nothing there when I shut my eyes and concentrate.

I would wager that without having done halucinogens a number of times, that score / my ability would be even lower.