They'd have to be brain dead for that to be true. In 3e they went with the traditional core and then expanded after. In 4e they went with a mostly traditional core(realized in a non-traditional manner) and then expanded afterward. In 5e...
WotC didn't realize after they designed the traditional core that people like new ideas. They planned it out that way as that's how D&D has been done since 1e. There's the core(what is traditional) and then splat books and Dragon articles to expand with new ideas later. And the tried and true method worked. 5e is hugely successful.
Can't happen unless the DM is just bad at innovating. What you can do for your PC I can do for an NPC. That right there is equal innovation. Only I also have all of the other NPCs to innovate with, world lore, monsters(old and newly innovated by me), geography, magical ideas, and more. There's far more opportunity for me and it's far easier for me to realize it.