Oh, there's crazies on both sides. Of course. But those kinds of nuts on the left are still very much the "fringe". You don't see GMOs, vaccines, and 9/11 truthism informing the Democratic platform, at all. Maybe you could call some of their platform "man-hating" or "pro-socialist" if you want, but that doesn't change the fact that their current platform and public rhetoric is not all that different from what the Democratic Party has been running on for the last 50+ years.
Even Bernie Sanders, the most viable left wing candidate the party has produced since FDR, might be sympathetic to GMO labeling, but is against a ban on them, and he's adamantly pro-vaccine. In other words, what you're talking about is stuff that's really more in line with the Green Party than the Democrats.
You can't say that about Republicans. The stuff I mentioned is either in the mainstream of the party, or makes up a significant minority and not just some fringe group. If you don't believe me, just take a look at the rhetoric coming from their candidates for president.
Marco Rubio accused Obama at one of the debates of wanting to overturn the Second Amandment, something Obama had already addressed as a "conspiracy theory". Rick Perry accused Obama of having "ulterior motives" in letting in undocumented immigrants. Most of the Republican candidates routinely accused the media of unfair questions and bias. They also took on political correctness and Benghazi several times over the course of several debates.
And that was just the nomination fight. In the actual legislative realm, Voter ID laws have been enacted by state Republicans all over the country. And the Republicans in the House have passed a resolution condemning the perceived "War On Christmas".
This isn't exactly "fringe" stuff that I mentioned in my original post. But the stuff you accused the Democrats of certainly is. If you think the amount of "crazy" in each party is fairly identical, just take a good look at who the Republican Party nominated for President.
That's not to say that Clinton is a good candidate, either, but the platform she is running on and the rhetoric she uses is certainly in line with what the Democrats have espoused for decades. It's an entirely different story with almost all the Republican candidates.
Here's some polling to back up what I'm saying. You're probably right on the 9/11 truther thing in the Democratic Party, but outside that, the mainstream Republicans dominate mainstream Democrats on the conspiracy theory front:
43% of Republicans think Obama is secretly Muslim.
30% of Republicans think Obama was born outside the United States.
67% of Republicans in December 2015 believed the media was biased against Trump.
In 2013, 41% of Republicans believed Benghazi was the biggest politican scandal in American history.
In 2012, 68% of Republicans believed there was a "War On Christmas", though that's down a bit more recently.
In 2014, 54% of Republicans thought voter fraud affected at least a few thousand votes in each election, and 36% of Republicans thought voter impersonation affected a few thousand votes in each election, the type of fraud that voter ID laws are designed to prevent.
In 2015, 53% of Republicans believed that the unemployment rate is now worse than when Obama first took office, when, in fact, the opposite is true.
etc.