I mean, did they even mentioned RxSwift somewhere?
Come on, it's obvious that Combine was made because the reactive programming was showing efficiency for years and RxSwift was prominent on Apple platforms. Given that impact made by the community it was easy for Apple to implement the same stuff with minor changes in protocol names. I want to stress that experience gathered by RxSwift is essential there. And now, when Combine released and old iOS will die out RxSwift will become less and less important, because native library always have an advantage.