The major problem Warren has doesn't have to do with double standards and leftist purity. Leftists weren't the reason that Democrats lost the general election, and they will still vote for her despite this idiotic maneuver. Her real issue is that anyone seeking to engage Trump's trolling rhetoric will inevitably fail, and will cause them to look weak and incapable in the eyes of "centrist" swing state voters. Warren can't seem to help but constantly try and "outsmart" and "outreason" Trump, which is a Sisyphean task. The more she tries to address his attacks, the more the conversation shifts away from policy and towards a perception of meekness and impotence. Anyone who is still on the fence about Trump obviously doesn't care about all of his awful qualities, they only care about who they perceive will stand up for them.