Firstly, instrumental? who? lmao I did 6 years of study doing literal classical sociology (which is basically just heres marxist canon) and i've got 0 idea who tf this is. I have studied post-modernism however and structural Marxism so hopefully I can give a informed perspective on this.
Structuralists are alright, thinkers like Foucault, Steven Lukes, Althusser and Bauldrillard have both put out things worth reading. I will say though, those are often promoted as being the canon of european marxist thought specifically because they are anti-soviet in thought; there very ability to be considered elite and high society in a liberal society is a requirement that they hold these views, otherwise they would have suffered the same fate as Gramsci; locked up in a mental asylum or prison for having intulectually honest views on Stalin, Marx and Lenin; Or like Claudia Jones, deported from America for speaking postively about Lenin.
The anti-soviet marxists of the 1960s-1990s in Europe unfortuantly drank the kool aid about fascist and liberal propoganda.