Earlier quoted context omitted.
Jeremy Corbyn has praised Karl Marx as "a great economist", FWIW.
Karl Marx WAS a great economist. Is this something one is no longer allowed to say without being smeared as an extremist?
He really was not. He was great at politics. He was great at taping into things that workers cared about.
But his actual economics that he laid out, in Das Kapital? The actual mathmatical equations in it, and falsifiable predictions in that book? The labor theory of value?
All pretty worthless. Basically no serious academic takes the labor theory of value seriously. It is non-sense.
Heterodox economic theories are heterodox for a reason. That reason being that they are not reflective of reality.