The funding model for journalism is advertisement. Advertisement generally follows the line of more views = more money. We call "clickbait" and "viral" stories that get viewed by the most people, regardless of their content. This means that journalists will focus on "clickbait" rather than a niche story that only a tiny fraction of their viewership will read.
Also, sourcing and vetting clearly take time, which could instead be spent producing more "clickbait" stories. Unless you're oversaturating the market, producing more "clickbait" is the rational action over producing quality journalism.
Furthermore, quality journalism requires expertise, which costs more. Compared to that, "clickbait" stories require adopting a certain writing skill which is in much larger supply. Thus follows that you would hire "clickbait" writers instead of journalists, because you'd be paying them less for more profit.
Really, pretty much every incentive in journalism fights the naivety of "professionalism" and "integrity", so it's little wonder that the state of journalism is as it is.
I am reminded of a short anecdote I read on HN the other day. People say they want sugarless yogurt, but every market research shows that they actually prefer the sugared variant. "We" say we want "good journalism", but clearly more people are reading tabloids and "clickbait". Whether that is because "we" are the minority, or because "we" are hypocrites is unclear, but that's reality.
