I see "high concept simulation" and "narrativism" as a spectrum (to use Forge terms I really don't like), not radically opposed.
My instiinct is do disagree with this, but it would be good if you could say a bit more.
The reason for my inclination is to disagree is that I think there is a big difference between (i) the goal of evoking, and remaining faithful to, genre, and (ii) the goal of making a thematically interesting or meaningful statement via play.
A practical example from my game, which has a bit of resemblance to one of Balesir's hypotheticals upthread:
The PCs were investigating a demonic ritual in an old temple. On their way through, they had rescued/captured/joined with (it was a bit ambiguous what verb was appropriate!) a tiefling devil-worshipper, who was in the temple also trying to stop the demonic ritual. The tiefling tried to encouage the PCs to seek diabolic boons for assistance, and one PC in particular was leaning this way, but the wizard PC - who had already been established as very hostile to diabolic forces - spoke strongly against the idea, and in the end prevailed.
After the PCs had stopped the ritual, without diabolic assistance, there was an explosion of chaotic energy that caused the temple to start collapsing. The PCs and the tiefling NPC started fleeing to the entrance. As this was happening, the wizard PC decided to kill the tiefling NPC with a magic missile. Mechanically, this was resolved as an Arcana check to "minionise" the NPC. I (as GM) adjudicated it this way for two reasons: (i) there being no larger combat on foot, there was no point at all insisting on use of the regular combat rules; but (ii) by requiring a skill roll, I created a chance for the other players to have their PCs react to the situation - it wasn't a fait accompli that the player of the wizard would get what he wanted.
The skill check succeeded, and a magic missile killed the NPC. The other players (and their PCs) were shocked. Their conception of the wizard PC changed significantly.
In high concept simulationist play, the main issues here would be things like the conformity of the wizard PC's conduct with his alignment, linking this to the alignment and metaphysical nature of devils and devil-worshipping, etc. From my perspective - admittedly as someone who is generally not that keen on high concept play (Call of Cthulhu one-shots being an exception) - I see it as mostly about
constraints - constraints which, in practice, it is the GM's job to enforce.
As it played out at our table, though, my main job as GM was to work out a mechanical method of adjudicating the wizard player's action which also created space for the other players to get involved, all in a fashion that would permit the players to express their own thematic/evaluative points. I see it as not about constraints on expression, but creating the space to permit expression. As experiences at the gaming table, I find these very different.
But like I said at the start of this post, it would be interesting if you could elaborate on your spectrum idea!