A movement of the left made up of self-interested groups is no movement at all. The first, second and last rule of movement politics is solidarity. Any movement made of people or groups which will sell out the rest of the movement is not a movement, and they will be played off against each other to give cover for the worst sort of policy. If you are interested only in your own issue, whether that is environmental, gay rights, women’s rights, immigration, trade, unionization or whatever, then you are part of the problem and your willingness to betray is why the left fails over and over again.
Hang together, or hang separately, as Ben Franklin said.
The left has chosen to hang separately.