This is a bit how propaganda works.
A 'fair' election is where parties stand for policies, and people pick the one they think is best.
Propaganda starts to enter when a party emphasizes and hypes areas it's stronger, and de-emphasizes areas it's weaker - so not that is IS better, but that people are giving more weight to the areas that benefit it.
The better they are at that, the more their thumb is on the scale and people get a warped view of the choices.
If they do it very effectively, it has voters wearing rose colored glasses where they support your party pretty much no matter what, and oppose the other party pretty much no matter what.
That's where trump's rhetoric is - imbecilic and obvious, but pushing this. So on November 4 election day, our country is an utter disaster because of the Democratic incumbent. Weeks later on Jan 20 the day he takes office, the country is the best in history because he's in office. It can make people get facts wrong, like saying trump did better than a Democrat on something where it's factually wrong.
And the most powerful factor behind which propaganda has the most effect, is money.
So this is where money essentially corrupts public opinion and buys and defeats democracy. It mattered less whether Bernie's policies were better, than how media had a near blackout on him an gave trump $2 billion of free coverage with his hype.