>Assange did not reveal a source for the leaked emails, and in fact claims the source is not Russian,
Assange's denials about Russia's involvement aren't credible on its face. The question is whether Russia hacked the DNC emails that Assange published. Assange fundamentally has no knowledge of the origin of the emails as the final stop in potentially multi-person hand off, unless he was involved in the hacking.
We also have multiple intelligence agencies, foreign and domestic, that have confirmed the source of the hack. Not to mention the context of the election, Trumps close ties with Russia and Russian agents, and the broad and multifaceted attempts at hacking the election attributed to Russia (disinformation farms, hacking state election networks), it is far past the point of reasonable to defend the theory that Russia didn't hack the DNC.
>You’re acting like if they had kept the manipulation of the Democratic primary a secret
But there was no manipulation. There were things that could be framed as manipulation, which people did, and that caused unfair damage to the Democrats and to democracy. It's like if there were two sellers of sausages and one of them had their sausage-making process recorded and leaked online. The other sausage maker goes "see their sausages are disgusting, buy ours instead!" all the while their sausages are made in the exact same way. It is unbalanced transparency that is inherently manipulative. It is a self-serving lie to pretend otherwise.
>It’s like if a sitting president referred to dead service men and women as “losers” and “suckers” you somehow think a newspaper causes harm by publishing that truth
No, its not like that. A sitting president's words are a valid source of news. The internal machinations of a private organization are not a valid source of news unless wrongdoing is documented. But no such wrongdoing was documented. It was all gossip and fodder for misrepresentation.