Assange and Wikileaks dumped the entire set of files, without redactions, while the Guardian, Der Spiegel, NYTimes were spending time and resources trying to redact them, and releasing them as they were ready, and Assange went around and blamed it on the Guardian.
He exposed them to destruction of reputation and liability that would probably have crippled and ended them if he hadn't backed off those claims.
Also, non redaction of documents, actively encouraging leaking, and actively doctoring documents are all things that Wikileaks (specifically Assange, according to the other co founders) have done and would be a massive game ending problem for any news organization if they as an organization engaged in such activities.