Another way to explain flattening of the demand curve is if you assume how much a person is willing to pay for a channel as a random variable. Then adding together a bunch of mutually independent random variables results in a sum with lower variance.
https://en.wikipedia.org/wiki/Central_limit_theorem
In other words, a bundle will have lower variance in how much people are willing to pay for it. Lower variance is great for the seller and buyer as they can price the good appropriately.
This is an interesting insight. I had never looked at bundles this way. My perspective till now was "Why am I paying for all this crap when I only need just these few things".
https://en.wikipedia.org/wiki/Public_housing_in_Singapore#Quota_system
Bundling of different ethnicities to reduce variance. Less variance means less "us v them" feeling and less tensions between groups.