Someone on reddit answered this quite well:
When you use your phone or read you are not actively thinking on the device that you are using, be so a book or phone; but rather in the content than you are consuming.
The content is what is relevant not the device itself.
That's why people have this myth that you "can't read" in dreams, in reality you can, but language is also a device for content, where the brain cares more about the content itself.
So you are more likely to dream about the content you consume, not the device you use to consume that content.
While it is "less likely" it is by no means "impossible".
But say you fix phones, or are a collector, or like me you are a programmer, maybe you are a writer; suddenly the device itself matters, so you will absolutely dream about the device, because the device itself is the content now.
From the brain's standpoint the phone is an extension of its perception, (and it is correct at that because the phone calculates, stores data, and performs communication in novel ways that your brain can't achieve, it extends the brain); and meta dreams are not common; think about how you use your phone, this social network right now, are you imagining a person writing this message and getting this content, or are you constantly aware of the fact you are just looking at pixels on a screen and there's no person?... no, you think you are discussing with someone, that's the theme; not interacting with a machine; hence the relevant theme is "discussion".