Just saying fraud doesn't exist doesn't help calm the outrage of those who believe it was stolen. Also based on how partisan the impeachment was it is likely people don't trust the government to have any sense of accuracy and merely attribute it to partisan lines.
The strategy of acknowledging what someone says and then responding to it often calms down difficult interpersonal conflicts. I think the same applies here.
We understand you believe "A", we do not believe that because of proof "B".
Instead the approach taken is largely ad hominem's which only escalate things further.