conquering 25 cities across the globe and keeping them together and productive for a few thousand years to attain a year 900 CE space victory isn't pretend to you? capturing every capital ever isn't pretend to you? neutering culture production in every other civ to attain a super early, 17 foreign tourists "culture" victory isn't pretend?
the whole game is pretend, so maybe you shouldn't be so dismissive of those who prefer an unrealistic peaceful victory over those who prefer an unrealistic domination victory. your "pretend" comment seems more of a political statement than anything related to the game of civ.
to say civ mechanics "dictate" military dominance is quite the exaggeration, as i don't think i've ever personally won a domination victory in the 24 years (on and off) since i first played civ even though i have won countless games. if military dominance was dictated as you say, i would have only won a fraction of those. i've done my share of 'conquering my continent' or wiping out the nearest 3 or 4 civs or whatever, it's frankly imo a boring and OP way of playing. it's quite baffling that so many people consider this the "good" way to play. i'd say it is more likely the game was designed (at higher difficulties) for early wars of conquest aimed at player's nearest one or two civs, and later on a few wars of defense and maybe one or two wars of expansion. any more than this and the rest of the game's balance breaks, and victory becomes a thoughtless steamroll. it's highly unlikely the developers meant for most of their game to be irrelevant, which is what happens with unchecked global military dominance.
If your opposition beats you militarily, you do none of those things. On the flip side, if you beat others militarily, they're not winning. You are, and you take your pick as which VC is technically attained.
That has been the reality in every single patch of every single civ game for more than two decades. You can win other ways, and since the AI is designed to throw sometimes winning other ways is easier, but in the mechanical sense and in terms of cost/tradeoff civ is and has always been military-first.
What the devs intended in any one iteration of civ is irrelevant to this consideration, because what they intended does not change what was ultimately implemented. That the game's outcome is frequently decided long before the game says so is one of civ's longstanding, glaring problems and a routine issue to address in 4x.
Regardless, it's not realistic to make a case that military isn't front-seat by design (accidentally or not) when you compare the costs of something like building a ship (and defending meanwhile while sinking those hammers!) to something like nuking the cities attempting it...which by the way also costs fewer beakers in addition to fewer hammers. If you're winning space in civ 6 (or any civ), you're either so far out in front that you can dump thousands of hammers into crap that can't fight and still hold up militarily or your opponents are throwing.
If you want to make a case that the micro to win militarily is boring, you're not wrong. I'd even argue that compared to games with competent or at least beta-level UI, you're objectively correct. It involves hundreds to thousands of inputs (many strictly not necessary under a better UI) during a phase of the game where the outcome isn't in doubt, and any single one of those move choices is close enough to irrelevant to the outcome that it isn't interesting. Civ 6 exacerbates this by making no credible effort to streamline the process, actively regressing in an objective #inputs fashion from previous entries in the series, which themselves are below par for turn-based strategy.
But that doesn't change the reality that military dominance is king in this game, even if you use it to win in some other fashion. That's how the costs are tuned. When I mentioned "playing pretend", my intention was to indicate that this has always been the reality in civ and that to say civ 6 introduced it somehow is playing pretend...not that the victory conditions themselves are. Obviously the game isn't realistic, nor should it be.