The Wall Street Journal asked in their Sunday op-ed how it came to be that

the party of the Kennedy tax cuts of the 1960s and the co-writers of the Reagan reform in the 1980s [became] implacably opposed to pro-growth tax policy?

The WSJ‘s editorialists should know better.  This isn’t their (or your or my) grandfather’s Democratic Party.  This is the Progressive-Democratic Party of Hillary Clinton, Barack Obama, Chuck Schumer, Elizabeth Warren, Nancy Pelosi, Steny Hoyer, and all of its rank-and-file politico members.

These politicians and their nine-year-old Progressive-Democratic Party that is the inevitable evolution of that prior entity do not want the folks who earned the money to be able to keep it and spend it IAW their own needs and wants and imperatives.  The Progressive-Democratic Party and its members need to have control over our money, and they are thoroughly dismayed over the loss to their political power that’s represented by the reduction in the amount of our money they’ll be able to control.  That’s power they’ll have much less of.

It has nothing to do with ideology.  It has nothing to do with income inequality.  It has only to do with political power.  It’s that nakedly simple.