Umm, I don't think I agree with you on the idea that decentralization decreases costs for contract distribution.

Distributing content to millions of people requires massive investment.

The total cost would likely INCREASE massively, as my home computer is much worse at acting as a CDN than Google.

Sure, the costs get DISTRIBUTED, to places where maybe you aren't the one paying for it. But SOMEONE is still paying that money. And they are doing much less efficient than a centralized service with thousands of engineers.