If you use the phone a lot, you are not generating any initiative on your own and are not reponsive to small initiations you dont notice. You are responsive to when kid explicitely comes to you.
Or otherwise said, if you are on the phone a lot, you are creating a barrier to interaction and people (both kids and adults) will eventually end up tired of trying and having less reciprocation.
If you are not physically there, it is actually less frustrating to others then if you create a barrier while being there.
The signal is also clear when interacting with adults: the people “over there” are more important.
These days I was “on call” at home and had to be able to answer my phone urgently. And I hated the fact that I needed to glance at my phone at every notification when talking with other people. Truly just having the damn thing is socially damaging.