Because we all know now that the politically weaponized FBI under Obama, was in the tank for Hillary.
That server, if it still exists, probably has tons of evidence against the DNC about cutting Bernie off at the knees in the primary and evidence that Seth Rich downloaded the damaging information Wikileaks got, instead of being hacked.
The DNC only threw Debbie Mayo Hair under the bus and fired her. She was immediately hired by Hillary's campaign.
Instead of running the DNC, she was now working for the de facto leader of the DNC, Hillary Clinton.
A difference without a distinction.
I read that it was server farm and it was wiped at some point and rebuilt from scratch. They would need server images or backup tapes to review log files.