If Trump had given the rebuttal, that would have played right into the TDS fever going on.
Nope.
Better to try to connect with the real swing vote out there: mostly White, but all suburban, women, moms and working mothers who run down the middle, a little Left, a little Right, and appeal to them to get out and vote for something other than the status quo by reminding them of their pain during this administration. Putting groceries on the table, getting the kid to soccer practice, worrying about the security of their families with increasing lawlessness, all due to policies of this administration, and absent while Trump was in office, or at least less prominent.
I think that mission was accomplished.
This was not a rebuttal for the true believers, it was a rebuttal for those uncertain of their future on America's present course, a reassurance that if they vote for Republicans that things will be Okay in the end.