Yes, and we should ask Lysenkoists about effective growing of crops.
Marx contributed massively to sociology. He contributed nothing of note to economics that's really relevant to this day (not that his effort was not commendable). Sticking to orthodox marxist economics in 2016 is more dogma than science.
Citing economic theory that has been discredited as evidence that economics is not a science makes about as much sense as citing Ptolemy's Geocentric model as evidence that astronomy isn't a science.
Marx's contributions to sociology are definitely relevant today, even if they're not in vogue. Even if they're wrong. This is human behavior we're talking about, and people have memories that they act upon.
Marx contributed massively to sociology. He contributed nothing of note to economics that's really relevant to this day (not that his effort was not commendable). Sticking to orthodox marxist economics in 2016 is more dogma than science.