"It is difficult to get a man to understand something, when his salary depends upon his not understanding it!"
- Upton Sinclair
Selling advertising space rather than selling one's purported product is the epitome of the dark forces and banal moral failure that DHH talks about. But most YC and SV startups owe their existance to advertising, and they are psychologically resistant to admit such moral failure, no matter how obvious the costs to society.
More detailed arguments against the ad-supported "business model": https://news.ycombinator.com/item?id=7485773