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.