Not everything is a conspiracy or a secret plan, though many things are. Capitalists organize, call it it conspiring if you want. I think ideas and thoughts in the population can be modeled as a stochastic process, with some character defined by the external environment.

The thoughts and ideas which become popular are ones that add power to the ruling ideology and inverse are elevated, similar to positive feedback. Things that challenge the ruling ideology are suppressed by the ideology itself. For example:

Marxist ideas are countered more often and more powerfully because media is defined around Marxism's antithesis. Media/academia isn't a neutral force. A Marxist institution can't emerge in the same environment, thus the "neutral" environment is an anti-Marxist environment.

Within the stochastic process I define above, Marxist ideas, or at least ideas which generally challenge ruling ideology appear. The only difference is that they don't gain the same weight as other ideas. The environment has a negative and unpromoting influence on those ideas.

Popular ideas aren't popularized mystically. Ideas need a vehicle in which to move and fuel to grow. The vehicle is often capital and the fuel is the dominant ruling ideology. Who benefits from both? The capitalist class. I say all this to make the claim:

The most popular left trends in the US are not popular because they are correct, they are popular because they are allowed the most positive feedback within their anti-Marxist environment.

Marxist ideas, what I consider to be the ML line, only become popularized when the external environment takes a dramatic shift. There is clearly no dramatic shift in the ruling (most popular) ideology so the most popular left trends should be distrusted.