Every time this comes up, it has been explained how there are more pages to combat rules because that's what's needed to mitigate that portion of the game. You don't need as much page count when dealing with role playing aspect.
True enough, and that's a valid counter point to the argument of "look at how the rules are structured, how they have been structured in various editions, and easily identify what type expected playstyle those rules support."
This argument is like saying the game expects there to be 20x as many casters as fighters because spells take up most of the page count.
It's even sorta right, by accident. Look for instance, not just at the much greater space devoted to magic-users in the 1e PH, look for corroboration in the PCs remembered from the original playtests - Tenser and Rary and so forth, and even EGG's own character, Mordenkainen - all magic-users.
But, no, you can't just look at the structure of the game, no matter how objectively, and divine the One True Way in which its meant to be played.
Because there isn't one.
Which was the point of bringing up that old saw about combat & page count.
1. RAW, if you used combat as your first choice and ran the game like you would in say 4e, your PCs would die all the time.
Sure, but that's hardly fair to 1e AD&D. First of all, assuming RAW in 1e (RAW was coined for 3e, because that was the era when the idea that you could count on the rules in any sense gained some currency), when 1e assumed DM primacy over the rules. And, also, of course, in the simple sense that you couldn't run 1e like you ran 4e - it's simply impossible, as the tools to do so aren't there. 1e was a much earlier itteration, and it's rules simply weren't able to handle the same breadth of styles as later, more sophisticated systems. Not without, as you put it "DM intervention" (though, really, DM intervention /was/ assumed).
2. You didn't get hardly any XP for defeating monsters. You got most of it from treasure.
Depends on how the DM stocked the dungeon. Going just with treasure types, for instance - easy to do, since that's what's actually presented, you'll /only/ get treasure for defeating monsters (that are in their 'lair').
3. The vast majority of PCs only went to name level before retiring.
"Retired by name level, if they survived" would probably be more accurate.
A 9th level thief will only have an average of 32 hp. So even at higher levels, the risk of death remains and doesn't drop as much as you're presenting. An owl bear will rip that PC to shreds in one on one combat
Thief name level was 10th, and it was a decidedly weak class, you probably didn't make it to 10th as one without a CON bonus, some lucky HD rolls (or just a lot of luck in general) - or some DM Intervention.
And, yes, lethality dropped off rapidly. Monster damage potential and hps didn't balloon like they do in 5e, and player hps and saves did improve rapidly from 1st through name level.
So no, AD&D hasn't always been a combat first game. Anyone who's played AD&D anywhere near RAW knows AD&D was "combat as a last option" game.
Anyone who's ever played AD&D anywhere near raw never really played AD&D.
Only when 3e came out and PCs got boosted in power exponentially, and then 4e made it all about combat.
I get that 2e paid some lip service to the storytelling trend of the 90s and produced a lot of detailed settings that made tourism-style play almost interesting (and enough PC options that losing a PC might actually start to hurt a little), but D&D really did start as a wargame, and 3e merely came back to being open about that. 2e was the aberration in that sense, and, as much as 5e resembles 2e in many ways, a pretense of despising those wargaming roots is not one of them.