It doesn't always. But it very frequently does, in fact, end up that way.
It can, I'll freely admit. But it shouldn't.
That's why I said that designing a game this way isn't compatible with modern audiences. You are here admitting that the direct consequence is intentionally turning away lots of players. That's the whole point. That's the very reason why such mechanics are actively avoided in most TTRPG design today. It's not only not popular, it actively fosters greater hostility against itself when folks are forced to play that way.
I'm not at all convinced about this.
And what happens if someone uses it for bad-faith play? Someone uses it just to mess with one of the other players, or to get back at them for something they did elsewhere, or in an attempt to trigger a pissing contest, or to get "even" because the target player won the roll for an item this player wanted, or whatever else?
Then - with one exception - that player can find another table.
The one exception is when everyone proactively decides it's brawl time, at which point all I-as-DM can do is sit back and referee. IME when there is a storm like this (quite rare) it usually blows over pretty fast.
This is only true if the conflict in question actually is unavoidable, hence why you used the word "war." If we instead changed it to "alligator wrestling", the whole concept collapses because that's obviously a ridiculously dangerous thing you don't have to do.
But which is "foster CVC conflict" more like: a literal societal-level threat where the outright destruction or domination of your home and people is at stake, where your choices are "fight or surrender"? Or is it more like alligator wrestling, meaning, a thing you can do, if you feel like it, but unless you're a real adrenaline junkie, why would you?
You can tell I fall on the "alligator wrestling" side here. Pretending that CVC conflict is an absolutely unavoidable thing that you can only either cower in fear from, or face boldly, is so many stacked bad arguments, I'm struggling to pick which one. (Appeal to emotion, appeal to virtue, false dichotomy, bad analogy...)
Then perhaps I should put it that those who have wrestled some alligators come away tougher and stronger (or dare I say, more experienced) than those who have not; never mind they're also now better at alligator wrestling.
Perhaps so, though the root came from the assertion that magic should cause harm to other players' characters through no fault of their own.
Two things here:
"Should cause harm" is too strong; I'd more go for "could cause harm".
Also, bad luck and bad aim happens. If a fighter can miss with an arrow shot and shoot the wrong guy (via a confirmed fumble, something I strongly believe should be in the game) then a mage should be able to miss with the placement of a spell and sometimes hit the wrong people.
I'm not saying these things should happen all the time, more that they should be able to happen at all. Quite literally on topic for this thread, even - magic should be able to, on a bad roll, go places the caster doesn't intend.
The problems arise when a player has their mage either a) be intentionally careless with their aim or b) blast a surrounded front-liner on the logic "I'll knock off five of them at cost of hitting just one of us" (which from the caster's standpoint might sometimes in fact be the optimal thing to do in the situation).
Which, again: making character archetypes specifically designed to cause problems for others as one of the costs of using that archetype's features? Yeah. That's a direct anti-player, high-frustration feature. Smart game design for games made to be cooperative doesn't do that--it leaves such things as an opt-in choice, rather than opt-out.
The way I see it adventuring is a dangerous profession, adventurers are dangerous people, and accidents happen.