Hussar
Legend
As I said in my earlier post, Greyhawk is low magic not by right of the rarity of magic items or the number of casters but in the power level of the casters. Yes, some remote places you can see some casters up to level 8. But 8th level has never been considered high level. Usually (or should I say,historically?) high level has always been considered 10+.
I'd say 9th because that's name level and when you get followers. But, that's maybe splitting hairs. The difference between 8th and 10th isn't exactly a huge, particularly in AD&D. 1 5th level spell? And, again, when you start going through the modules, you realize that high level NPC's were pretty much dime a dozen.
Greyhawk has many casters, but the vast majority of them are below level 9. The high level casters are rare and far between. If you compare Waterdeep in its 1ed inception and Greyhawk in its 1ed inception. You'll see that Waterdeep, as a comparable city, has over 10 named wizards over level 12, with one that's level 27+ (depending on the level of the highest player) to a meager 3 named ones in Greyhawk and Tenser does not even live in the city proper.... Only one 9th level cleric in Greyhawk and 9 in Waterdeep.
The difference is not in the power of magic but in the numbers of people able to weild the most powerful spells. Greyhawk has a lot less of those. But my guess would be that the amount of low level casters (under level 9) us about the same.
An arguable point.
You can't also take into account the number of magic items from 1ed vs 5ed. A single magic sword, even without any "+" attached to it has more power than a +4 weapon in 1ed. Why? Because there are no longer any creatures hit by +5 weapons only. Any magical weapon can hit any creatures, this is a big power boost compared to 1ed.
But, you're still hitting far less often and doing less damage per hit. That's a very debatable point.
Also, in the adventure modules, it was expected that the characters might find about half or less of the magical items listed. Some were so well hidden that one group in 10 found them. It was quite rare for a group to find every single magical items of an adventure module. The 5ed assumption is the opposite. There are less magical items but their placement almost make it a certainty that they will be found (almost, there are of course exceptions but they are rare).
This has been discussed and debunked. It's a complete myth. See Quasqueton's adventure discussions on this site for details. You might not find every single item, but, you were most likely going to find the majority of them and far, far more than "half or less". Most were in plain sight and easily found.
AD&D defaulted to over 10 magic items per PC. Proof: Paladin's were limited to 10 magic items. That was a hard restriction which could cost them their status if they went over. If no one ever reached 10 magic items, then it wasn't much of a restriction was it? The presumption is that AD&D PC's would be absolutely dripping in magic items by name level.
This is why I consider Greyhawk to be low level in magic. Not in the power of the welders, but in the amount of of its high powered weilders.
This is a setting where multiple gods walk among the people. Cuthbert, Iuz, Vecna, Kord, just to name a few. Where you have magic items and casters around nearly every corner. Where fantastic monsters appear all over the place. I strongly disagree with this description of Greyhawk.