this actually sort of reminds me of Hypernormalization and the idea that the failure of the left in the era of neoliberalism is its failure to present any sort of compelling alternative to the current status quo. After ceding power entirely to the right in the post-Reagan world it could not present itself as a compelling alternative, only a nicer version of the status quo. For all the (real) talk of the Southern Strategy killing the New Deal era, the social democratic left in the entire first world fell apart and parties that haven't adjusted to that are collapsing (PS, SPD, Labour until just now).
It's interesting how much of the vanguard of the new insurgent left really are just social democrats from before the total collapse of the social democratic left, Bernie isn't really all that different from a New Dealer just updated a bit for the 21st century, but the ideas are largely about returning to the past. Much as I love them, I think part of why the insurgent left struggles to take power is that it can't quite formulate its alternative other than in terms of a return to pre-1980s social democracy. It's something I think you've touched on indirectly when you criticize Sanders' trade stances.