The far right is seriously outnumbered. Encouraging people to apathy helps them, because most people who get involved are their enemies.

Personally, I think both sides have their issues, but the issues the right has are waaaay worse than the issues the left has.

So just saying “both sides have issues” makes it a binary argument when the degrees of how negative their issues are really matters.

Two possibilities:

1. Apathy - people stop voting for parties that can be a counterweight to the far right.

2. Abbreviated analysis/Feelings over facts - people are more likely to fall for politicians presenting themselves as underdogs who are going to revolutionise the political landscape, which is a strategy fascists like to use. "Drain the swamp" is a perfect example for that, and if I remember correctly, there were a lot of potential Sanders supporters who voted for Trump. I know both are more or less opposites, but both provided a canvas for people's feelings that "politicians are all the same" and that fundamental change needs to happen. The latter is true, but with proper analysis shouldn't lead to voting for the far right.