It depends a bit by what you mean by left and right, but if you take something like Marxism that was always 100% a propaganda effort created by people who owned newspapers and the pervasiveness of propaganda has been a through line e.g. in the Soviet Union, agitprop etc. A big part of the Marxist theory is that there is no reality, that social experience completely determines everything, and that sort of ideology naturally lends itself to the belief that blankets of bad faith arguments for "good causes" are a positive good.
This sort of thinking was unpopular on the left for many years, but it's become more hip no doubt thanks to countries like Russia and China trying to re-popularize communism in the West.
