Dems are supposed to be able to talk frankly about their beliefs without the left wing of the party destroying them. There shouldn't be political consequences from within the Dem coalition for saying "I don't think we should have trans people in professional women's sports". Since the Dems can't talk about the policies, the right wing gets to take up all the attention on them.

Some Democrats do. Kara Dansky of Women's Declaration International, for instance.