Strikes a chord for me too. I came to Seattle from the midwest where I lived in a Craiglist house with a gang of besties. I met some people here (also via CL shared housing) but since I've paired up and settled in it's been really hard to maintain good relationships with friends. I looked out at the skyline and though, geez there must be tens of thousands of people within a mile radius, none of whom I have any means to communicate with. I was going to do a nextdoor-like startup for sharing tools, rides, events, etc. (it was too be called "neighborcasting") but I didn't pull it off due to engaging day job.
I've also been discouraged because it seems like very many people simply do not want to meet the people around them. For instance, check out this recent thread on the SeattleWA subreddit about talking on the bus [1]. I was kind of flabbergasted by how much people hate it when a stranger talks to them.
It's like there are just too many people and no one has time to connect with any of them in an unplanned fashion.
[1] https://www.reddit.com/r/SeattleWA/comments/8stzn9/featuring...