Find me a single example to the contrary, or a link where an experienced professional provides an example. Just one. If you're not wrong, step up and provide examples that supports what you're saying.
Its not a fact.
Remember, all I'm saying is that designs change during development.
This is a fact, and I'm not sure why you're so persistent in trying to disagree with it, especially given it's a fact that doesn't actually diminish the point you were originally trying to make. Designers are more valuable because it's true, and would be less important if they were no longer needed after writing a GDD.
It strikes me that it's rather unfair of me to demand you to provide examples without providing some of my own. I did already provide the example of Quake, but you've dismissed that, and whilst I disagree with your reasons it's a rather easy matter to provide more examples, so I won't argue the point.
Firstly we'll start with a little anecdotal support from right here in the topic:
- In reply #36, Hodgman is talking about his own industry experience, and mentions that "no-one uses the waterfall model where the product matches your very first plan".
- In numerous replies, SimonForsman tells mentions that it is true for his own experiences as a hobbyist developer.
- In his article on Game Design Logs, successful indie developer and experienced industry veteran Daniel Cook recommends an alternative to traditional game design documents, and says that "game design is a process of informed iteration, not a fixed engineering plan that you implement" and that "it is an essential quality of a game design that it evolves over time."
- In his article "why you should share your game designs", the same writer (Daniel Cook) says that "the final game is not going to look anything like your initial game design because ultimately it is the game director who makes the most important decisions, not the person who writes the game design document."
- In his article Why Design Documents Matter, experienced developer Ernest W. Adams (who lists his experience as "23 years as a design consultant, lead designer, producer, and software engineer in the game industry, following 7 years as an engineer in the CAD industry.") says that "video game design is a highly collaborative activity, far more so than the movies. Unlike a film director, whose rule is well-nigh absolute, few designers are allowed total control over their game."
- Halo developer Bungie are well known for their idea of finding "15 seconds of fun" and then making it repeatable by iterating on their design. You can see them talk about this in the documentary on the special features disk, or read about it in many articles online (such as this one).
Game designs change during development. It's just the way things are. The fact that it's like that actually supports your original idea, so I've no idea why you're so insistent in arguing against it. Go on -- admit you were wrong and move on -- you just might grow as a person and learn something.