Very true. Most Americans don't know actually what socialism is, it's just a synonym for "bad." I don't think anyone that describes themselves as one is going to do well with most US electorates, even though the tenets of socialism line up pretty well with their actual beliefs.
The DNC is corrupt and sucks, but they're right to fear this association. If they embraced the socialist messaging today at the party level, they'd likely lose every election outside of the major metro areas and become even more irrelevant than they already are.