Why would a political party categorically shun any large and diverse demographic group?
The "white working class" in the US includes large numbers of people who are young, unmarried, irreligious, or enrolled in public benefits - all groups that vote heavily for Democrats, to the extent that they vote at all.
The Republican Party ignores minorities and see how that helps them? (Not). These white working class voters are natural Democrats, in many ways. The Democratic Party should be smart enough to bridge the Silicon Valley types with the white working class types.