Probably to speed up the process of background checks so dems cannot grind it out past midterms
Yes, exactly.
If you explained to people on the street how few of Trump's appointments to Main Justice have been confirmed by the Senate, here a year and a half after taking office, they would be shocked.
Allowing the normal document production by the DOJ for Kavanaugh to be handled by the Obama leftovers in Main Justice would lead to a high chance of delay and sabotage and not getting it done before the October Supreme Court term starts.
Look at the job the Obama leftovers have done in foot-dragging and redacting when it comes to satisfying congressional and FOIA demands for documents that might show wrongdoing during the Obama administration.
I take this as a sign Trump and Sessions are serious about getting Kavanaugh confirmed promptly and they will not allow it to be sabotaged from within.