This is simply not true of OD&D (meaning specifically the 1974 version). Most racial special abilities (bonus languages, bonus at listening, dwarfs' "contruction" skills (noting slanting passages, shifting walls, etc.), elves' spotting secret doors) are non-combat-oriented, most of the class descriptions deal with non-combat matters (building castles and establishing baronies for fighters and clerics, creating new spells and magic items for mages), about half the items on the equipment list have no combat utility (rope, 10' poles, iron spikes, lanterns, mirrors, rations, etc.), at least half of the spells are non-combat-oriented (and even more are mixed-use: spells like invisibility and fly can be used in combat, but also out of combat) as are many of the magic items (ring of water walking, bag of holding, wand of secret door & trap detection, helm of reading magic & languages, etc. -- even magic swords often have non-combat-oriented special abilities such as detecting gems, traps, or secret doors).
Volume III does include fairly extensive rules for aerial and naval combat, but it includes even more extensive rules for non-combat dungeon exploration -- listening for noise, spotting traps and secret doors, opening stuck doors, detailed rules for running away from (i.e. not fighting) monsters, advice for placement of treasures (with monsters or traps to guard them -- but note that the focus is on the treasure being guarded, not the monster doing the guarding), examples of tricks to get players lost and screw up their maps (teleporters, one-way doors, chutes and slides, rotating rooms, etc.), and an example of play that details all the non-combat activity and glosses over combat completely: "(Here a check for surprise is made, melee conducted, and so on)."
Likewise, the section on wilderness adventuring has details on getting lost, running away from monsters (again), and dealing with inhabitants of castles (which may involve combat, but not necessarily), and the rest of the book covers miscellaneous non-combat topics including construction of castles & strongholds, hirelings (which does include men-at-arms but also non-combat figures such as sages, alchemists, and animal trainers), gathering information, rumors & legends, character upkeep, and establishing baronies.
Coverage of combat in OD&D is limited to 2 pages of tables and some spell descriptions in Vol. I, the monster descriptions in Vol. II, and the aforementioned aerial and naval combat rules in Vol. III -- maybe 1/3 of the pagecount tops. It seems highly unlikely to me that anyone could read these rules with an open mind and come away thinking they're 90% about combat. Yes, it is described as a "wargame" on the cover, but that's simply because at the time there was no term to describe the type of game it actually was -- about exploring the unknown, gathering treasure (which often, but not always, involves fighting guardians for it), and developing a "character" over the course of months (or even years) of play from a simple flunky into a powerful baron, wizard, or patriarch. Combat was a part of the game, maybe even the most prominent single part, but it was by no means the only, or overwhelming, expected activity. That game was Chainmail; D&D was something different, something more.
