IMO the correct analogy would be a physical object where you could switch back and forth between Harry Potter and books used for learning. If that were the case I'd agree with you. But here we are talking about two separate distinct physical objects, the Harry Potter book and, for example, a biology book.

When a person is reading the latter they can't easily switch to HP, but I can do that while learning anything in my computer. It's as easy as doing ctrl + T + red + enter and I get to the infinite entertainment that is Reddit thanks to the browser autocomplete, for example.