Comment by petsfed
By just about any reasonable accounting, the willful deconstruction of the concept of art reached its peak during and after World War I (e.g. Dadaism), specifically because of the wanton and apparently pointless destruction of an entire generation of French, British, Germans, and Russians (and others besides, but they bore the brunt of it). There was a very widespread questioning of traditional mores, which arguably bolstered the broader Marxist cause, but its definitely an inversion of causality to say that Marxism caused existentialism.
But, Dadaism, for instance, was a far left movement. Its followers, were people that held radical or even far left views. [1]
Marxism is really a cancer that destroys everything it touches. Its final aim was always to destroy everything that is beautiful, elevated or pure about mankind, and we, as a society, have been sponsoring it with our taxpayer money that pays for the self anointed gatekeepers of intellectualism that populate a big part of our Academia - that is to say, all Academia that doesn't get judged by the outcomes of their ideas when applied in practice.
[1] https://en.wikipedia.org/wiki/Dada