We can squabble over definitions, but a primary characteristic of Platonism for many people is the belief in a (separate) domain of ideals/concepts. That e.g. mathematical objects exist outside of our individual cognition. That's more dualistic than monistic.
Plato is generally considered to be the archetype of early dualism. What are your credentials?
> Please don't post shallow dismissals
> Please don't pick the most provocative thing in an article or post to complain about