Is the end of truth the end of democracy?

Here's just one example among very many of the post-truth world we live in today.

At a boat parade in Jupiter, Florida, in support of Donald Trump (yes, I know, a boat parade!), some of the boats were openly displaying swastikas and neo-Nazi insignia and changing racist slogans. When there was an outcry from Democrats about it, Trump campaign officials merely claimed, with no evidence offered or attempted, that it was a "false flag event" by "liberal activists". 

This, in spite of the positive identifications of known members of the Order of the Black Sun and the Goyim Defense League (yes, these are the names of real neo-Nazi organizations!)

This kind of spurious but effective shut-down has now become the first line of defence and attack, almost a knee-jerk reaction to any potential set-back. There is no longer any attempt at making the argument convincing, or at least partially true. It is enough to provide social media with an alternative talking point, and to parry and negate any potential political damage.

So, if all that's needed to shut down a legitimate protest is a barefaced, unfounded lie, then what is the value - what is the point - of any protest, any debate? Given that the majority of Trump's election campaign at this point is based on random unsubstantiated claims and outright lies, often, it seems, conjured on the spur of the moment, what is the point of even trying to refute them?

Trump's supporters will apparently believe pretty much anything he tells them, either out of ignorance or out of willful suspension of disbelief, there seems to be no legitimate way he can be stopped from lying. Many other populists, from Netanyahu to Orbán to Erdoğan to Poilievre, have taken this approach, often with great success. Most of them have taken their lead from Trump, who has single-handledly moved the Oveton window on what is considered politically acceptable. 

Is this, then, the end of democracy as we know it?