How are the Democrats so powerless now?
Why are the SDP in Germany losing election after election?
Why are the Socialist Party in France about to be eviscerated?
Over the last 20 years the centre-left parties of the world gave up on opposing the current economic system and instead decided to embrace it, along with it's wealthy donors, and instead focus on "moderating" neoliberalism with this or that minor concession for the poor. By this point, they don't even bother to do that, they are literally carbon copies of the conservative opposition.
The result? No matter who wins which election, the wealth gap got bigger and bigger and the financial industry became less and less regulated and the global economy more and more volatile.
Now we face the terminal decline of that model of economics. The beginning of the end was 2008 and there has been no meaningful recovery since for the vast majority of the working class population of the developed world.
They're sick to death of the status quo and want change, but the left has been so completely annihilated by this coalition of the centre-right and centre-left that the only alternatives being offered are those on the far right: Trump, Le Pen, Brexit.
Which is why it is truly depressing to see people ITT still falling for that coalition's desperate attempts to cling onto the power they are now inevitably going to lose, by discrediting even the most minor shifts to the left (eg. Corbyn).
So long as the education middle classes who would traditionally have joined the march towards a new progressive society are as ideologically brain dead and completely delusional as they are now, there will be no meaningful left wing reaction to the collapse of neoliberalism and so absolutely no chance in fending off the advance of the far right.