If there wasn't going to be any social interaction anyway, there's nothing to detract from. I read books on my phone in public places - e.g. subway stations and

If there wasn't going to be any social interaction anyway, there's nothing to detract from. I read books on my phone in public places - e.g. subway stations and trains - all the time. But some places and times are intended to be more social. If you're at an explicitly social gathering, at a party or happy hour, dining with friends, etc., and your face is buried in your phone the whole time, that's rude. You don't owe others your time, but neither do you have the right to turn a shared social space into something else for your own benefit. If you want to be alone, get to a less social space. Everyone including you will be happier for it.