These are realities that the DNC won't face because it threatens their donors. SF is a bad example as a region on a neoliberal stranglehold that is only nominally leftist, but much more concerned with money. The political machine there is adept at crushing upstarts. Nancy Pelosi had a serious challenger several years ago; she refused to debate him, and bad actors with Pelosi connections torpedoed his efforts with specious harrasment campaigns.
Which is all to say that the DNC and its local arms go out of their way to actively scuttle anything that doesn't have their seal of approval. Hope in SF, Kentucky, and elsewhere is not a function of progressive electoral capability, but of establishment Democrats' willingness to play fair or dirty.