When I got back into comics in 20008, I wasn't as sharp of a grader as I am now - so I overgraded years ago, and when it came time to sell - I graded down to reality and took a loss.

In reality, how could anyone not like a book like this. VF/NM and printed 2.5 years before Action 1 and representing a time from the depths of the Great Depression.

That book is a freak of nature.

The market created itself. CGC is just a reaction to it.
Collector's already gauge the value of the same book in 9.8 by White Pages or not (which CGC does designate) but also by how the book's cover was cut and properly stapled.
Collector's have long sought out and paid more for UHG books for their rarity since at least 1970 when the OSPG began publishing. Read Mile High Chuck's Edgar Church story and see how quickly word got around about that collection and how fast some of those collector's moved in to scoop some of those books up.

Interesting responses.

I guess I understand the urge to have your comics in the best condition possible, even if as some alluded to, it might be just collectors' OCD.

I think I miss the time when just having a certain comic seemed to matter, as long as it was not falling apart. Now it seems having a certain key issue is not enough, but you have to have the issue In a really high grade. Maybe I'm misremembering how collecting was before CGC, But it seems like the strict condition of comics wasn't as big a concern.
I also think that old comics in low grade condition are interesting, because they can almost tell a story by their condition. You see a beat up Amazing Fantasy 15 and can imagine that it once belonged to a kid, and maybe was stored in an attic somewhere and somehow arrived at a dealer decades later. Comics in more 'perfect' grades have none of that history and character. I still have the first comic I ever bought and it's in fairly beat up condition and probably worth only a few bucks at most, but I love it more than any other comic I own. I could easily go out and buy exact issue in perfect condition, but it wouldn't be the same to me.

Easy answer. The market of digital 9s was created because people figured out bronze,copper and modern comic books are virtually worthless in near mint. They figured out that near mint copies are not rare at all because of all the bagging,boarding and hoarding between 1976 and up!
So they had to create an artificial market to make some money.
9.2, 9.4, 9.6, 9.8 then 9.9
Some day we will see the 9.9 and a half!

Why buy high grades?

You are mis remembering how things were before CGC. I have never liked low and mid grade books. I just get zero pleasure from owning and looking at them. Even 15 years before CGC I was paying multiples of guide for high grade books.

Comics in more 'perfect' grades have none of that history and character.

I agree, seems highly unusual to find a book that old in such perfect condition. I've always wondered how such a thing happens. Everyone seems so concerned with getting the correct boards and bags to store their comics, and keeping them away from light and humidity. Yet this comic survived unscathed for 75 years without any of our modern protection. Where was it stored I wonder?

I may look for a higher grade but to me I really want a presentable grade over a higher grade. For example I went after a book in a recent auction where there were three copies listed.

Copy one was a 8.5 with a date stamp
Copy two was a 8.0 with a clean cover
Copy three was a 5.0

I went after the 8.0 with a lot more dedication than the other two books. In fact I basically ignored the date stamp cover.