i would guess one effects the other in a negative (positive?) feedback loop. access to your phone & 24/7 easy access to social media started to erode communities and now people just rely on their phones because they have zero community around. there is nothing interesting to look to if you look away from your phone because the rest of the people around you are on their phones. EVERYBODY is glued to their devices every second of the day. waiting in a line for a coffee? have to stare at instagram stories. a random boring moment where you are allowed to be alone with your thoughts and maybe observe other people around you and get to start talking to someone? why? you have your twitter feed full of rage & engagement bait.
the only thing these days that actually can foster any community is playing sports. thank god we at least still have that. can't exactly pull your phone out in the middle of a basketball or volleyball game.
I agree it's related. But that it's glaringly obviously the cause? I'd need to hear more.