The "left" has - same way as the "right" - always been defined from the need to rally a mayority of the political power in order to rule. In Denmark and Norway we have today parties that are called Left - Venstre - as a result of being founded at a time when the defining charactheristica of the left/right divide was related to a) universal and equal voting rights and parliaments power over the executive and b) the abolishment of inherited economic privileges. The scene changed and they ended up on the right, but the party names stayed the same.

So I would disagree, there never was a coherent line of thought, only worse or better narratives.

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