While technically true, I think it's overstating things. GW's miniatures designers (the step in the process right before sculptors, people like Jes Goodwin, the man responsible for the look and style of the Astartes, the Eldar, and scores of other factions since the late 80s) do a lot of conceptual and thematic design work that informs the whole design process, from sculpting to writing. Yeah, the miniatures come first because GW is a miniatures company that happens to make rules (with a side of "IP farm for licensing"), but it's not exactly individual sculptors and their whims.Honestly, I think it's just a sculptor had an idea, and GW doesn't really care much otherwise, that's just how they are. Remember, this is a company that doesn't even make rules for something or conceptualize it for the rules side, they just make rules for things their sculptors make.
Also this.They are people who share at least some space with each other. The rules people are at the very least going to spend some part of their lunch talking to the designers and gush about how cool it would be to have a transport for the Ad-Mech just as the design person is going to wax poetic about the little plasma manifold they scultped into the interior of the land raider and ti would be cool for that get a shout in game and so on.
It doesn't sound so different from how the last couple of video games companies I worked for do things, especially with the increase in the 'skeleton core/plus DLC' development approach that is becoming the norm in larger studios. They don't make a game to be standalone and one-off, and after the base game's out, marketing, the designers and the developers have a structured process of developing DLC.<snip>