The Hindu and Buddhist traditions had already said all about what the modern philosophers tried to say?

Philosophers like Descartes, Plato, Socrates, Kant and so on came after the Hindu and Vedic traditions and these guys just involuntarily plagiarised philosophies that are said in Hinduism about the nature of reality but these modern philosophers get all the credit for what was said in the Vedas and Upanishads. Why is that?