It is a modern witch trial. The purpose is to set an example to deter the public and especially the media, and to ensure that the media does not release information about state misconduct in an uncontrolled manner.
In 20 years of work with victims of war, violence and political persecution I have never seen a group of democratic states ganging up to deliberately isolate, demonise and abuse a single individual for such a long time and with so little regard for human dignity and the rule of law
Also the Council of Europe (in section 6.2 of Resolution 2317) join the recommendation:
Assange’s extradition to the United States must be barred and that he must be promptly released
See also a recent interview with Thérèse Juel in Swedish (the part about Assange starts at around 46:30 into the video).