During the primaries, voters have the opportunity to select a candidate whose views approximate their own. For years my response to those who claim that Democrats and Republicans are all the same has been to ask if they participated in a primary contest. And that is the reason for the similarities between the general election candidates. The primary is where voters have the ability to move what their party stands for. It is only during the primaries that Democrats, or like-minded independents, can push the party away from the policies that have hollowed out the middle class, incarcerated millions of black and brown bodies, and result in deadly and destructive military actions overseas.
Democrats were angry at President George W. Bush (R) for the war in Iraq, but President Obama (D) toppled the government in Libya and has, intentionally or unintentionally, provided weapons and resources to ISIS aligned groups in Syria's bloody civil war. When it comes to targeted assassinations, many of which have killed civilians and some of which have killed American citizens, the Democrat leads by a mile in terms of body count.
During the 2008 primaries there was a candidate, Dennis Kucinich of Ohio, who had he won the nomination and the White House, would likely not have authorized Hillary Clinton's Libya strategy or increased the use of extra-judicial drone killing overseas. That is a real world example of how the primaries, not the general elections, determine the policies of America.
So if you sit on the sidelines and ignore the primaries, don't be surprised when, come November, the choices all look like dog shit. If you cede the selection of the candidates to people who love dog shit, that's what you end up with. Furthermore, democracy requires a more substantial commitment than once every four years. As Samantha Bee so magnificently illustrated, the 2010 election was more important than 2008 and yet the turnout was less than 38%. You know what, just listen to her: