Depends what one means by "mainstream." RT and Sputnik do a little coverage.
Also not mainstream, TJDS and Chris Hedges cover it.
Furthermore, the growing problems of conspiracy theory cults is partially due to incompetent leadership and lack of journalistic integrity by those at global microphones leading to a dissolution of trust in authorities. The obvious solution to better journalism isn't an alternate reality, but by higher-integrity journalism that is sustainable and independent on the whims of mercurial "family products" executives with undue influence to have anchors fired. And that can had only by outlawing corporate, ad-supported journalism that creates evil, corrupt business model-reinforcing dark patterns and replace them with grant- and subscriber-based journalism.
Also, government-supported news, like BBC, RT, and Sputnik, is a terrible idea because it creates the appearance of a conflict-of-interest in holding government accountable. The Fourth Estate must be separate and independent.