That is not correct. There is a guideline that says productions should try to ensure a certain number of behind-the-camera crew fit certain minority statuses but this doesn't come at the expense of skill, is not necessarily rigorously enforced and doesn't apply to the casting.
The simple fact people like to ignore is that the actors were hired due to their acting ability, as evinced by the praise piled on Sophia Nomvete and Ismael Cordova. What you're actually advocating for is that these actors and others should have been passed over for less capable people based on their skin colour alone.
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Also Aragorn, Faramir and Boromir should all have been beardless and the Orcs should have been more like Hobbit size without the weird tumour-faces. It's funny how people are quite happy to accept changes for "modern audience" expectations unless there's a chance for them to whine about skin colour.