Are they so bad at socialising that they can’t meet new people?

People tend to go the easiest route, and AI gives them the opportunity to do so. That is the problem with AI in general: No effort is needed anymore to archieve anything. You want to create a picture? Just type the prompt instead of learning (and failing) to draw. You want to write a song? Just type the prompt instead of rhyming the lyrics and learning (and be bad at it in the first time) an instrument or two.

Maintaining any social relationship means that you have to put in more or less effort, depending on the quality of the relationship. Having a relationship with an AI model means that you can terminate it and start over, if you feel that the AI model is mean to you (= if it provokes another opinion, or disagrees with you - because arguing and seeing things from a different point of view means putting in effort).

In the long term people will forget how to interact with people in order to maintain meaningful relationships, because they un-learned to put in the effort.