I'm a member of some parenting groups on Facebook, there is a woman on a few of the same ones who regularly posts saying she's looking for friends as she's lonely.
She'll get lots of replies from others saying they'd like to be friends / have play dates / chat. I was one of the people who replied to one of her earlier posts and added her as I know as well as most how isolating motherhood can be.
Lots of the other mums across the groups have added her over time and as such her friends list is huge (in the thousands) but she doesn't reply to comments or messages from people reaching out, just adds them. I know this because the people who have added her often comment on her subsequent group posts asking for friends saying things like "I did send you a message" or "I'm still happy to chat if you still want to talk to somebody"
She does this every couple of weeks.
What is her motivation? It's a bit strange imo.