sounds like a waste of die space for non gamers.
This saying has been repeated like its a proverb.
The reality is absolute cost of silicon is minimal compared to what they sell them for. Silicon chips are a gold mine, because you take what's literally dirt cheap(sand) and sell it for hundreds of dollars.
Now the majority of the market don't care about discrete graphics, because iGPUs are more than capable of displaying high quality 2D, and Video. Heck, they do gaming ok too if you are willing to make certain sacrifices.
The majority of the market PAY for the minimal physical cost increase due to die size, and research and development costs. Once a chip is in mass production, it would be more complicated to produce another die that strips off the iGPU. And they would do it for what reason? To appeal to the purists?
Think about it. If one of the companies, AMD or Intel, did not have any part with an iGPU, they would be locked out of 70% of the markets automatically. That greatly offsets the tiny cost increase caused by bigger dies.
We could even flip that around and say for most folks they are wasting the dies on 4+ core CPUs by putting extra cores.