The 1e era didn't have one well playtested, copyedited, and produced book a year. The game of that time was poorly playtested, haphazardly designed, and had uneven editing and production values*. But still it was your "Golden Age"?
*Let it be noted, however, that I still like the game - I think that good ideas and style usually trumps solid playtesting and design.
This goes FAR FAR beyond and before the edition wars. Prior to everything there were the War Gamers, and we were glorious. If anything was balanced, the Wargamers would find it. They had an innate feel for what was balanced and what was not.
Afterall, when recreating Waterloo, would we want to have it so it always ended with Napoleon's defeat...what's the fun with that. A truly balanced battle would give the player that chance to upset history.
Wargamers had a different mindset than those who were new with RPGs. Many Roleplayers who were also wargamers would NOT admit to their wargaming buddies they played RPGs (I still don't most times these days).
There was bad blood between Wargamers and Roleplayers (but not as bad as that between the old Roleplayers and 3.X players)
Why do I mention this?
Because Gygax was a wargamer. Going back, he was that Wargamer who had that sense of balance. His take on the RPGs probably was more akin to what occurred in some Wargames in which you'd have players, and then you'd have the referee of the game. The DM in an RPG was the referee meant to handle disputes.
I find the original AD&D to be actually MORE balanced in relation to the old Wargamer mindset than anything that has come afterwards. Most of what came afterwards was catering to players and their wants rather than the actual game itself.
Which leads us to your comment.
Someone stated above that during the Golden age TSR was publishing one book a year. I'd say that's not even close. TSR printed a hardback occasionally, maybe once a year...if that...BUT they printed OOODLES of softbacks in the form of adventures and other items.
In many ways it was more balanced with that old wargamer mindset that Gygax had than the new Roleplayer aspect that came later.
It's hard to put into words the exact difference of these types of balance except there's a specific type of feel to it. UA had worn that sheen off (but was more for fun then balance anyways), 2e definately had the sheen wearing thin...and by the time 3e came around, there was no sheen of that type of balance at all.
There was a new type of balance (3e was in no way balanced in relation to that old type of balance...it catered to a different type of balance). At least how the creators of 3e saw balance, which I think is a very different type of balance than an old grognard may have seen it (no telling if the new grognards would see it that way though).
I would imagine your reference is to UA, and other books of that time period rather than the original book per year release of AD&D.
Maybe you are right in regards to some types of balance, but if you go that route you'd have to apply that same idea to the later books of any edition.
In 3e the books got more and more unbalanced as well in many ways, even in regards to the "new" balance. I think the rest of your post would also apply to 3e in it's later stages just as much as it does to the later TSR books for 1e.
2e started pretty early with the unbalancing act though, I'd say within the first release after core almost, or less than a few months.
4e, it's creeping relatively slower in that regards as far as I can see thus far...then again they say hindsight is 20/20. After 4e passes perhaps I'll be able to see the unbalancing act there as well.