The advertisements defray the cost of the thing you are
  paying for. If they weren't there, you'd have to pay much
  more for it.

Given that cable with ads averages over $100 a month [1] while Netflix without ads charges $14 a month for the most expensive package [2] I think the purported cost savings from having ads are not in evidence.

[1] http://fortune.com/2016/09/23/average-cable-tv-bill/ [2] https://www.theverge.com/2017/10/5/16429126/netflix-price-ra...