While I thought this was a pretty good article, the author is confusing what is an OTA vs a meta-search engine, even though he spends a paragraph explaining the difference. From one of the comments on the article:

* Expedia is not an aggregator/meta-search, it is an OTA itself. Meta-search engines are sites like skyscanner, hipmunk, trivago and kayak to mention some.

Another further confusion is when the author compares TripAdvisor with Hilton's own site. The screenshot even shows that TripAdvisor just redirects to Booking.com (Booking.com is owned by Priceline), who is the OTA.

The other thing the author doesn't discuss, but is an important part of the story, is that large OTAs spend billions advertising through Google, and are experts at it. Booking.com is the largest spender of any company on Google Adwords: https://venturebeat.com/2015/11/05/booking-com-largest-googl...