That used to be a few years ago, but it doesn't anymore. This is quote from Tony Stubblebine on another site.
QUOTE: Lost our way on recommendations. When I showed up the company was convinced that engagement equals quality. That's not true and it gets even more pronounced if you pay people to game your recommendation system.
https://news.ycombinator.com/item?id=34743772
This is another lot of comments from Tony - note he says nothing about getting people engaged. He is going where the money is - excellent articles. That is what he wants.
There is no money made by the company when they pay for comments from readers.