A competition is a form of combat.
No it's not. I've sat, and I've graded, competitive examinations. They are nothing like combat.
Even as competitoins, they are different - a race or an exam is an attempt to do better than another
at a common task. Combat is an attempt to best another by preventing them doing the same to you. And this can be seen in mechanical resolution terms: an attempt to adapt Runequest's combat resolution rules for racing would break down pretty quickly, because there is no analogue in a race (or an exam) of the Runequest
parry skill.
(Systems otherwise as different as BW and Marvel Heroic/Cortex+ Heroic are able to cope with this by dropping RQ's separate attack and parry stats, and resolving fights as opposed checks, which can also be adapted to running races.)
Furthermore, if all competition is combat then that generates obvious absurdities, like a poetry slam or battle of the bands being part of the combat "pillar" rather than the social "pillar".
The 5e "pillars" tell us about the design, and focus of play, of 5e. They are not, and don't even purport to be, a general analytical framework for RPGing.
look just a bit more broadly and ask why the vehicle is being repaired.
So does a joust belong to the
social rather than the
combat pillar if it is being done to win the heart of an admirer? At least as I understand it, the pillars are meant to be characterised by some combination of
what is going on in the fiction and
how that is resolved at the table, not
what it is hoped success in the action might facilitiate.
Nothing new was being explored but the travel still puts it in the exploration realm.
What information is conveyed by this? In 5e D&D, to describe it as "exploration" tells us something about (i) what is happening in the fiction, and (ii) how that will be handled at the table - in particular, via the back-and-forth of free narration between player(s) and GM, and perhaps the occasional check if the player declares that his/her PC looks around, or picks something up, or whatever.
In my Prince Valiant game, there's no back-and-forth here: there's just framing. To describe it as "exploration" in the 5e D&D sense is to actively misdescribe both the techniques in use, and the table experience.
In my Traveller game, when checks are made to successfully make an interstellar jump, there is a standard subsystem that is followed, and if the checks are successful then the next stage of play is to narrate the PCs's ship's arrival at the destination world. Again, it has little to nothing in common with 5e's "exploration".
On-world travel in Classic Traveller is much closer to 5e's exploration; it's for that very reason that I've repeatedly characterised it, in threads over the past year or so, as the weakest part of the Traveller rules, and disappointing in comparison to the tightness of the other sub-systems.
all 5e did was clarify and codify something that's always been there in the background probably without a lot of us realizing it was there.
Had this clarification come from some other source whose words you value more highly we probably wouldn't be having this discussion.
Huh? I've thought about different elements of play, and how they related to mechanics. long before WotC published 5e.
But taking a concept (the pillars) that just happened to come from a D&D edition and applying it universally certainly can and in my case does help understand or clarify how RPGs (can) work
But it's not doing this! It's leading you into repeated misdescriptions and mischaracterisations. For instance, the fact that you envisage travel in my Prince Valiant game as being like 5e D&D's exploration reveals that you
don't understand what is happening at the table. It's actually closer to your concept of "downtime", but that woudl also be misleading because it is occurring in the course of what you would call an "adventure".
WotC in 4e distinguished
exploration from
encounters, and distinguished the latter into combat and non-combat resolution. That is a useful framework for 4e; it broadly maps onto the Marvel Heroic RP/Cortex+ Heroic distinction between transition scenes and acion scenes, although the latter have no combat/non-combat breakdown.
It would just distort understanding of 4e to insist that social skill challenges be thought about differently from travel skill challenges, or to insist on analysing travel skill challenges through the lens of
exploration as that concept works in 4e.
And mutatis mutandis for other RPG systems.