For all of you, who are wondering what's a list of websites doing at the top of a business model post. Please read - The next paragraph or two would be around search engine rankings and paid media.
This image shows the who's who of quality content websites in various niches from Tech, news, lifestyle and so on. Important to note is that majority of these web properties that drive millions in traffic belong to the same publishing house. A slew of recent deals in the media and publishing business is taking the publishing world by storm and consolidating the search results on engines like Google even more in favor of these large publishing houses.
Look at the below image that shows first page of Google when searched for a particular keyword related to Gaming. The same thing happens in almost all major niches (Tech, Finance, Dating, Recipes, Health, Auto etc.).
What this essentially means is that the publishing property (and thereby the owner publishing house) can control the entire customer lifecycle from the various properties that they own around a central theme. How would the lifecycle be controlled is an interesting point to note.
Because of a search metric called link juice (technically a referring website). Basically all these properties belonging to a single publisher keep moving the customer within their own ecosystems by referrals, and by default if they come up with a new web property, they can drive insane amount of traffic (and thus authority) to that property and drive up the search engine rankings of their new property.
Recently DotDash (owner of Investopedia) announced that they may buyout Meredith Publishing for $2+ Billion. These M&A can consolidate the power in the hands of few publishers (with a vast list of web properties) that they literally can dictate ad prices (native ones and not the Google or other ad-network ones). They become the gatekeepers of the customer's eyeballs. Which also clears the air around their business model heavily being reliant on Advertising!
Let's say you were a large Bank and would want to acquire high net worth customers for a variety of services that you think you can provide them. One of the few places that you would want ad-networks to target is Investopedia and other top content publishers in the space. With the above assumption and image, look at the customer demog of Investopedia and thus the CAC to drive traffic and acquire customers via CPM/CPA model would be huge.