On the mainstream media. I think there are things they unfairly get the blame for, and others not. They have definitely pushed a line of making “big news” of everything, so that it becomes very hard to know what is today’s minor event being pushed big for clicks versus, actually, today’s news is really really big! They have also not always had the level of self-checking we would hope for, although in my view this is far more often due to budget cuts than bias (and I’m not including Fox News and conservative radio as MSM. With them its bias).
But there is also the issue that people don’t want to consume uninteresting media, or get nuance any more. You say the media had a go at McCain and Romney like they were Trump, and you are right that they weren’t him. But they did push the same policies. Both had to move so far to the right to win the Republican primary that it was very clear both were running on a similar policy basis as Trump. Not quite as extreme, but then the media wasn’t as extreme as Trump. And Palin was every bit as extreme as Trump.
The problem is, nuancing a discussion to say that Romney/McCain are not so bad per se, but their policy position which they’ve staked out to win the Republican primary is terrible, is just too complicated.
One other headache is that the media loves free hits. They’ll show and promote Trump’s grand daughter talking in Chinese at the presentation, and also any own goal. When you have Trump, Bush and Palin (and others) doing own goals as often as they do, its no wonder they get a lot more air time than Obama did. When Trump is writing the media’s headlines for him in twittersphere, of course they take him up on showing how silly he’s being again. Of course, that all then feeds into the right’s argument that the media is picking on Trump more. Its not the only reason (they’re also writing more because his policies are diabolical and he’s making the USA a laughing stock), but it certainly adds to it.
Your points on people moving to insular news that supports only their views is also spot on. And people then want to refute anything evidence based over “what they’ve heard”.