Phantoms were
And while I agree that technically the arc has more physical seats, we all know in Xwing seats do not equal the number of crew slots.(see any large ship, or the Tie Phantom, or the Bwing title) so that's kinda moot. We saw it in an actual movie(that the game is based on)
It's not at all moot. It's not a one to one relationship, but number of in-lore crew is indicative of crew slots in X-Wing.
Phantoms were two-seater, with the second crew member not specifically dedicated to anything, though I always kinda thought of them as akin to a systems engineer, but I guess our fearless designers didn't see it that way.
B-wing/E2 modification was explicitly an extra seat in the craft.
I will grant you that large ships don't get as many as is relevant, but that's far more to do with game balance than anything, and I'm willing to allow a certain amount of fudging in that particular direction...
You seem to agree with me - it's not a direct one to one relationship?