Why are the Democratic Primaries so close?

If you looked at the Democratic primary race previous to this summer, Biden and Sanders seemed to be the two main contenders. The race has expanded though, with Warren joining the two at the top of the polls, and Buttigieg rising rapidly through the polls as well.

And yet, with mere months to go before the primary elections, voters still seem unsure of who to vote for in this primary. For example, Iowa, an important swing state, 62% of voters said they might change their mind again before the caucus. As more and more candidates crowd the playing field for Democratic nominee, it becomes harder and harder for the voters to discern the minute policy differences between them and create a candidate for the party which has a unified backing from the major political pillars. And it is a unified backing that's needed for whoever wins the Democratic nomination, because voters outstandingly just want someone who can beat Donald Trump in office.

And while the large amount of candidates and choices in the Democratic Primary race means that there is division within the party, it doesn't necessarily mean the party will fail in the general election due to party tensions.

All together, voters overwhelmingly want Trump out, where 63 percent of Iowans told the Register having a nominee capable of defeating Trump is more important than having one with policies they support. Regardless of whether there are a dozen or two candidates in the Democratic race, it simply is a reflection of the different factions of the parties and should not have any bearing on the presidential race of 2020.

Sources:
https://fivethirtyeight.com/features/yes-the-2020-democratic-primary-is-still-crowded-thats-not-necessarily-bad-for-the-party/

https://www.vox.com/policy-and-politics/2019/11/21/20970931/state-of-2020-democratic-presidential-primary-november