when IIRC, most of the philosophers were claiming at this point that causality was a mere illusion of correlation?

That this isn't at all the case should be obvious even if the only thing you've read on the subject is Pearl's book. The entire counterfactual approach is due to Lewis and Stalnaker. Salmon's theory isn't about correlation either. Also, see James Woodward who has done very similar work to Pearl but from a philosophy department. Pearl cites all of them if I recall.