I'm an "Apple user" that switched from iPhone/iPad/Apple Watch to Android alternatives; while remaining a happy user of Macbooks.
The statement doesn't make sense because people don't keep 2 phones in their pocket, or 2 smart watches, and rarely have 2 tablets that are actively used. And people definitely move between ecosystems. Choosing one excludes the other, and they have equivalents for each product type.
Hence they are direct competitors.
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The real problem is that the mobile OS & app store market is a stable duopoly.