The general thought is that without a “front runner” there is no where for enthusiasm and the feeling of backing a winner to form around.
It appears that the candidates of the party see no pecking order hierarchy within their group, why should voters see them as any more than also-rans.
I like how Georgia seemed to count over four million votes on election night in 2016 faster than they’re counting these 150,000 or so.
Turnout is the key. The Dems are energized and motivated behind one candidate, who has a huge amount of money and the support of the MSM and Hollywood. The race has become high profile because it is a way to continue to attack Trump and boost the morale of the Dems for the midterms. The Dems are desperate for a victory in much the same way the Reps were in 2009 when they took the governorships in NJ and VA.
Also, having many candidates may prevent Rs from getting a recount.
Don’t know Ga details but as a rule a specific candidate has to be close to demand one.