From that point of view, I'd suggest that the current problem isn't really the destruction of gatekeepers but rather swapping one set of mostly positive external influences (such as traditional journalists with strong professional ethics and critical reporting standards, and genuine expert commentators) for another much less positive set (such as online services that provide communications for the masses, but not in a neutral way, and media spin doctors as commentators).

You mentioned Brexit and Trump, which are case studies in the way people can be influenced by political campaigners, but I find a lot of the criticism of both of those results to be one-sided. After all, it's not as if the official Remain campaign in the UK or the Clinton campaign in the US were telling the truth, the whole truth and nothing but the truth either. However, there's less to be gained by fact-checking the losing side once the result is in.

Another recent example that I find more interesting is last week's UK budget. Much has been made of the announced rise in National Insurance rates for self-employed people. It's a controversial issue, because some people do exploit the tax system to pay less than they should by changing their employment status, but also because a lot of people who have never been self-employed themselves really don't understand how it works and tend to leap to conclusions that are objectively wrong. Sadly, rather than starting a potentially useful debate about different ways of working, different levels of risk/reward, and how the tax system should treat them, what has started is a discussion about how the party in power lied (because they gave a manifesto commitment before the last election not to raise the rate for this particular tax), and who can be made to fall on their sword this time to serve the entirely political purposes of who else.

In all of these cases, I think we would have been better off if we'd had a culture that fostered open debate and welcomed but looked critically at advice from those who might have more knowledge or understanding of any given subject. There are a lot of ways we could achieve that, but none of them involve communication channels that seek to influence which messages get through to promote a particular side of the debate. That threat is, in my view, even more serious than politicians who are blatantly lying, because we know some politicians lie a lot and can be sceptical accordingly, but without access to other information as well that scepticism might not make much difference anyway.

>their honest fact-checked newspapers

Of which newspapers you are talking? I don't think such a thing exists.

The New York Times, The Wall Street Journal, The Washington Post, The LA Times, the Guardian etc... plus AP and Reuters.

They all have trained journalists, sub-editors, and fact checkers. They all correct errors when they make them.