Started doing this to a limited extent. For years I'd have never dreamed of doing this, as I did not want to feel obliged to casual acquaintances, i.e. I feared expectation of friendship that I did not want to reciprocate. Turns out most people are just happy to leave things casual. I don't mind small talk.

Related to why I've had limited friendships. I've wanted fewer, high quality ones as overshooting my social needs is uncomfortable, and I'm a creature of habit. Used to overcorrect towards solitude and that backfires, but I've had friendships in the past where I dreaded having to meet.