A game isn't a fundamental or structural part of a system. In the end, it is just a game. The goal of a game is to deliver an experience. It doesn't need to be scalable or robust. If the experience isn't marred by bad coding or bugs, then it can still be a great game.
Yeah all of that is always going to be true across hobbyists, indies and small studios. But for commercial game development at scale, where there's multiple studios or outsourcers/co-devs brought on, there's real expectations that people can be on-boarded quickly and work productively on projects with tight schedules. A poor quality, fragile codebase (usually with technical debt) is a recipe for disaster when things are at being worked on at that level.
A game isn't a fundamental or structural part of a system. In the end, it is just a game. The goal of a game is to deliver an experience. It doesn't need to be scalable or robust. If the experience isn't marred by bad coding or bugs, then it can still be a great game.