The conversation with
@Nagol was about "soft-balling" (I brought this precise point upthread if you recall) and not classical Force.
It was the fact that the 6- (which is a failure and mark xp) result in
World games will have occasions where a Soft Move is more appropriate than a Hard Move. Navigating this will rely on all of the principles and directives of the game.
For instance, it is an extremely rare occasion where a Hard Move makes sense for a Spout Lore in Dungeon World. There are some occasions where a Soft Move makes more sense on other moves that come up 6- (when the arrangement of the fiction doesn't have any imminent/present threats to deploy to immediately invoke a Hard Move and nothing makes sense from a strict follow the fiction principle). However, if you've already telegraphed something prior with a Soft Move, then its appropriate to follow through on that and invoke a Hard Move.
For instance:
A Wizard is in a summoning chamber of a Warlock. There are glyphs scribed in chalk on both the floor and the wall; the former forming a circle and the latter in the shape of a door. As the Wizard approaches to inspect the wall's "door glyphs" you describe them subtly pulsing with a soft red glow, incomprehensible whispers in a tongue long forgotten to the ages accompanying it. Visions of violence and torcher assail the Wizard as he draws nearer.
The Wizard pulls out his Bags of Books (+1 to Spout Lore per use) to consult his collected knowledge on summoning glyphs, languages, and the words used to turn them on and permanently shut them off. On a Success, the GM tells Wizard player something interesting and useful. On a 7-9, the GM tells the Wizard player only something interesting; its on them to make it useful.
Despite a +2 Int and the +1 for the BoB, the Wizard gets only a 6. The Wizard marks 1 xp. The GM activates the portal (a Hard Move) and an Abyssal horror skulks through the gateway (because of the setup - Soft Move - above). Without the appropriate fictional circumstances and the setup framing, the GM should deploy a Soft Move. Same thing goes for anything without immediate obvious physical fallout. Its basically tantamount to Controlled Positioning in Forged in the Dark games.
This is easily the most difficult and nuanced part of
World games, one that later iterations and the Forged in the Dark games (Blades) have cleaned up pretty much entirely (Blades Position and Effect does all the heavy lifting for this as mentioned above).