Unfortunately a lot of these require either an existing network or high stakes interaction (sending invites, accepting invites etc). They're good advise, but can be hard to execute on for most people.

If we want to solve this at the society or community level, there needs to be more opportunities for low stakes interaction. Places that people can passively gather around a communal activity. I'm reminded of the ladies dancing together in public squares / parks in China. They're usually a group, but mostly anyone can join in. You can just follow along and interact as much as you'd like. If you want to leave, leave. If you want to stay and chat, stay and chat.

Downtown San Mateo for example has the potential for this. It's already a closed off street where people go. But today there aren't group activities there that encourages passive interaction, people are still in silos. Perhaps if there were some games / puzzles, chalk boards, townhall type of table setup, that'll encourage passive interaction.