I speak with my friends on my phone. Sometimes I may speak and laugh for two hours with an old friend I, for family/life reasons, haven't seen for years but with whom I have this ability to instantly resume our customary banter.
I read books on my phone. I do prefer a physical book but after I started a job where I travelled a lot I actually started buying the electronic versions, and once I got a phone with an OLED display it is quite okay to read on it in the dark. I read at least an hour a day.
I think the "problem" is that any phone usage looks the same. If you are sitting with your calculus book you look "usefully busy", but not if you're studying on your phone. If I read a thick novel I look serious and smart, but with the book on the phone I look like I'm scrolling on Facebook or whatever people use nowadays. If I watch a lecture on computer science I appear the same as if watching anything else. Is "phone" itself bad, or is it just that it looks the same as if one is being "lazy"?