That’s because people are apt to believe those sources and not critically question them.
The exceptions are local news about local events that has no political angle, and occasionally investigative journalism.
The most common method that legitimate news sources use to bias news is by omission, and second by using a misleading context. Neither is strictly a lie, but the result is as much fake news as something fabricated.
Pizza-gate is bonkers, but that doesn't mean there isn't a healthy segment of the population that believes it as a way to channel their collective hatred for someone. Which is itself just a way to solidify their group identity, much the same as the resurgence of flat-earthers who feed off of their own ignorance while proclaiming their supposed objectivity.
I think the reason people are downvoting your comment (aside from the obvious reason, which is that it's a little low-effort) is that people didn't like pizzagate. It had an altright, Trumpy 'beware the deep state satan pedophile illuminati' feel to it that we oppose being true for identity reasons (ie, we are not those people who say trollish, unintellectual things like that!).
Although pizzagate is false, it's not as false (in a kind of Bayesian way) as it was before the Epstein island entered the public conscience.
Overall, I just have a hard time imagining the details of how it would apply in today's world.
It's not the primary focus of the story, but it does at least quickly attempt to answer these problems to advance the narrative in a reasonable way.