The Democrats have long understood that the unmarried, the unbelieving, the deviant, and immigrants tended to vote for their party.  So naturally enough they have tried to increase all these categories.

The reason they won’t stop coming after you is because their isn’t an ideological objective they are trying to achieve.  They are trying to keep and maintain power in a democracy.  For that purpose they need to keep penalizing you and keep rewarding their constituents.

They have been pretty open about this program for a long time.  See the Emerging Democratic Majority,  see this recent NYT article from Democratic operative Stanley Greenberg, or any of the crowing from the left about soon turning Texas blue.