The goal of supporting of Democratic Socialists is to promote those who would weaken capitalism but more importantly they wake people up to the class war. I hope that with Democratic Socialists gaining popularity it will create the material conditions that promote revolutionary thought.
IMO, Section J.2.7 of An Anarchist FAQ makes a pretty compelling argument against endorsing any politician as an anarchist.
For any Mamdani supporters scrolling my history: my non-endorsement of Mr. Mamdani for Mayor of New York is a principled objection to electioneering. Mr. Mamdani seems like a good socialist and incredibly decent man, and I wish him success in his activism even if we disagree on the necessity of the State.