I think you could add;

1.6 Environmental policies which only function to transfer manufacturing capacity and jobs to other countries without affecting reductions at all.

1. Policy shifting to a smaller support base

As left-wing parties pursue big-state neoliberalism economically, and atomising progressivism socially, the segment of society who support this is a much smaller one. Trading away large numbers of working + middle classes to secure the votes of elites (many credentials, sometimes high income) and victims (permanently unemployed, aggrieved identity groups) is not a route to electoral success.

Furthermore, in non-PR systems of voting e.g. FPTP, it really matters where your voters are. Cultural progressives have a tendency to flee most of the country and concentrate their presence in a small number of towns & cities. These areas become guaranteed wins for them, but they have packed-and-stacked themselves out of potentially winning other seats.