I don't think a new player to D&D which was the premise would know that.
70s was Chainmail, or? That was only about combat.
And wasn't it Arneson and not Gygax who at first expanded upon this framework?
It was about OD&D I believe. I disagree that OD&D was only about combat.
I do think Gygax thought combat was an important factor for D&D throughout his life. For example, from well-after AD&D came out:
"Melee in AD&D is certainly a crucial factor...As melee combat is so common an occurrence during the course of each adventure, brevity, equitability, and options must be carefully balanced."
He talks about balance a lot actually. Like this quote on racial limits and it's role in balance:
"The character races in the AD&D system were selected with care. They give variety of approach, but any player selecting a non-human (part- or demi-human) character does not have any real advantage. True, some of those racial types give short-term advantages to the players who choose them, but in the long run, these same characters are at an equal disadvantage when compared to human characters with the same number of experience points. This was, in fact, designed into the game. The variety of approach makes role selection more interesting. Players must weigh advantages and disadvantages carefully before opting for character race, human or otherwise. It is in vogue in some campaigns to remove restrictions on demi-humans — or at least relax them somewhat. While this might make the DM popular for a time with those participants with dwarven fighters of high level, or eleven wizards of vast power, it will eventually consign the campaign as a whole to one in which the only races will be non-human. Dwarves, elves, et al will have all the advantages and no real disadvantages, so the majority of players will select those races, and humankind will disappear from the realm of player character types. This bears upon the various hybrid racial types, as well."
My bottom line point is that focusing on combat in this thread does not equate with a belief that non-combat aspects of the game are unimportant. People have repeatedly asked that you stop inferring that. At this point, I am asking, do you just think people are lying to you when they say they don't believe that?