While someone can question my experience of course, I'm going to say Traveller--where one of the two commonest campaign models (the other being merchants) was playing mercenaries is still pretty heavily combat oriented. Nothing I've seen suggests that isn't routinely true about Rolemaster either. I won't speak of the others because I only know them by reputation, but I don't think they change my position in general
In my Classic Traveller campaign, only three PCs are combat-oriented. And only one of them has a suit of powered armour (Battle Dress in the game's terminology). Other PCs are technicians, spies, socialites, etc.
The campaign is neither merchants nor mercenaries, and so perhaps does not count as typical. But it doesn't depart from the core PC build or resolution rules. The resolution rules include, as well as combat, interstellar travel, flying spaceships in normal space, some aspects of on-world travel, social interaction, buying and selling, some aspects of construction and repair, and medicine. Probably the single most common resolution framework that has figured in our play is social. We have had plenty of sessions which do not include combat.
Rolemaster has plenty of combat, although again I have run sessions without combat. But in the first RM campaign I ran, one of the principal contributions from one of the longest-lasting PCs - a mystic - was social and espionage.
In 12 sessions of Torchbearer, 3 have featured no kill, capture or drive-off conflicts at all, and only 2 have included kill conflicts. The most common sorts of conflict are social (negotiate, trickery, convince, convince crowd); again, I think only 3 sessions have not featured any. Of four PCs, only 1 has Fighter as their highest rated skill; they started with Fighter 4. The same character also has Dungeoneer 4, which did not start that high. But the highest rated skills in the party are Loremaster and Scholar (both 5) on a character with Fighter 2.
Prince Valiant, being a fairly light-hearted Arthurian game, features plenty of combat, but of our 3 knight PCs only two are skill in Arms or Battle. The third is social, and physical but not fight-y (a bit like a classic D&D thief). When his player needs to actually win a one-on-one fight, he either hopes to get lucky, or plays a Storyteller Certificate that lets him win without needing to roll.
What distinguishes these systems is that they have robust, binding resolution for non-combat situations. (With RM perhaps as an exception - it's non-combat resolution is not entirely robust; but is not hopeless either.)
I think the poster I was responding to was suggesting balance could include competence in different areas--but even in games that aren't as combat oriented, I don't think that helps much; it just moves around what the important areas are, but I'd be willing to put a substantial bet that games where activities don't heavily lean into one particular area are rare.
I make no comments on what is rare or not rare. But as per my post that you quoted, I don't regard "balance" and "combat" as being especially related - I regard
balance as pertaining to
the mechanical capacity of the players, by the play of their PCs, to impact the shared fiction of the game.
Part of how Traveller works, at least as I observe it, as that there are sufficiently many different pathways to impact that the wildly varying numbers on the PC sheets (a result of random generation) don't inevitably produce wildly different capacities to impact the shared fiction. Eg even if your PC's Vehicle skill is quite low, if you're the only one who has it it gives you a distinct pathway to impact.
Another dimension of capacity to impact the shared fiction, which I find important in my RPGing, is that the group of PCs is often not just a many-headed hydra; and in such circumstances, the way for a player to try and get the impact that they want is to declare an action for their PC. Upthread someone (maybe
@Gradine?) mentioned GM-guided spotlight sharing as an aspect of, or pathway to, balance. I think that players declaring actions for their PCs to get the impact they want as the player-driven counterpart to that.
