It has become ridiculous with these booking sites. When you google a small hotel, often the first many results are hotels.com, bookings.com, tripadvisor.com etc. and the hotel itself is down to spot 3, 4, 5 or even lower. There is a place for the booking sites, especially for exploring several hotels at a time. And they do offer some reviews and comparisons that can be useful. Sometimes, they also offer the cheapest…
And it really feels good to pay the hotel that offers the services, instead of some tech company in the US." Most of the times I booked through booking.com it was "cash on arrival", so these sites are nothing more than ads. I think the problem is travel agencies, that book bulk of rooms to rent them later (just a guess, can't read the article itself due to paywall).
Expensive ads. Cash on arrival does not mean that the hotel does not pay a sizable commission. Roughly in the range as the cut iTunes, Play, Steam take for transactions that, unlike hotel service, create zero cost beyond the initial investment. Occasionally, hotels might even offer you a cheaper room if you cancel your reservation, to get out of that obligation. Maybe some sites are much cheaper, but the big ones like booking.com take everything they can, and they can take a lot.