@darkbard already gave you an excellent, full answer, but I'm going to answer this in a way that is a commentary on the thread's premise + how Tier 4/5 Blades in the Dark play diverges from Tier 0-3 (and especially 0-2).
Why Tier 0-3 Blades in the Dark is one of the only few successful Gamist/Narrativist systems:
* (When the game is run well/correctly and played well/correctly...drop this preamble in for all of these) The decision-spaces a player navigates is persistently consequential and persistently intricate in its engagement at both the tactical and strategic layers where lines of play evaluated and selected are trivially evaluated for skillfulness (employment of system, examining and managing connected risk profiles, managing precious resources, playing the fiction, and creative/lateral thinking that involves the integration of both of all of those simultaneously).
* The bulk of play features you, as a player, persistently saying something both chunky and consequential about your character, your connection to Friends/Rivals/Vice Purveyor/Crew/Crew Ally & Enemy Factions & Contact/Duskvol/Deathlands/Supernatural Entities. There are consistently pivotal moments of character evolution (which often features dissolution in some shape/form) where you're prioritizing one of tactical, strategic, thematic/premise-based over the other in which you have to make a sacrifice due to the inherent tradeoffs and incentives baked into the game engine.
Why Tier 4/5 Blades in the Dark suddenly falls down in those Gamist/Narrativist aspects and veers Neotrad:
* Scale just fundamentally breaks the game at these Tiers of play. The volume of Cohorts/Gangs/Experts (including your access to Allies' Scale) under your control is staggering. The game engine just can't handle it. At the same time, the same volume arrayed against you via your Enemies does the same work but in the opposite direction.
* Powerful Sorcerers or high Magnitude supernatural entities (see Lord Scurlock) add their Scale to their Tier? I mean...what does that even mean in the fiction? Its basically a numerical patch to make someone like The Emperor completely untacklable; (Tier 6 + Scale 6 = 12 total Magnitude...its impossible to, within system, get the
Position : Effect matrix to anything that isn't
You're Dead : No Effect).
* Action Dots + Resistance Dots + Special Armor access + all the various add-ons/multipliers (on multiple axes) just overwhelm the system. At Tier 4/5, if you're tackling anything that isn't just absurdly devastating (with ridiculous fiction that is hard to even array the imagined space with such that you're generating the intimate and compelling decision-spaces of Tier 0-3), you're basically mapping your preferred PC/Crew conception & arc onto play.
Your ability to resolve situations/obstacles becomes effectively stakes-free fiat. S
takes-free fiat = player-side railroading even if every aspect of the rest of the system forbids it. You're no longer Going Boldly Into Danger and Embracing the Scoundrel's Life. You're overwhelmingly just generating your preferred fiction and gamestate.