I think part of what tends to get missed is that while AAA game development certainly has software development as part of it, it's a relatively small part of the overall project from a person power and cost perspective. It's not uncommon for a ~200 person game development team to have only ~15 software engineers on board, with the rest being on the game development side (game designers, animators, artists, level builders, game logic creators, testers, community managers, marketing, etc).
It's also not uncommon for the internal tooling that gets created to allow the game development folks to build out the game to dwarf the actual game code is size/scope. There tends to be a large upfront effort from the software engineering side to get the engine ready and the supporting internal tooling ready for the game designers to go to town, after that it can be years in the game development process with only bugs, maintenance and smaller feature additions to the engine/tooling for the software dev side of the process.
With such a lopsided time investment schedule between disciplines you need to be either a massive company or only work on games with a small scope to achieve smooth employment for all involved.