This is a great question @CreakyCrank thanks for asking it. I am replying to this thread to bump it up the feeds to hopefully get some discussion going. Looking forward to hearing what others think.
I agree, there are multiple elements that define Strava as a social platform:
1. The ubiquitous feed of activities as any social network.
2. The fact that you can join multiple clubs, which by definition are a social congregation of people
3. The leaderboard, segments, KOM/QOM, and other competitive attributes.
As such, Strava should devote more resources to enhance the social elements of the platform to build that community. Is great being able to join clubs with like minded people from around the world, but I also belong to a few clubs that I meet with IRL every week. Other than tagging that you rode with someone there's not much more than you can do as a club member. I also belong to a swimming club, swims are not joined up as rides since you don't have the GPS location, but would be nice being to group them afterwards.
I ride outdoors every day and would love to see some more useful social features. Strava clubs could be a great way to meet and communicate with other riders who share a common interest, but the way clubs work now it's impossible to create one that doesn't get filled up immediately with people who feel the need to join every single club. I don't care about some random dude in Indonesia riding on Zwift and clogging up the leaderboard. I would like to be able to see and compare myself to other people I might not know riding in my local area. It would be great to be able to use the club post feature to contact other local riders but with the number of club spammers out there, the members of most clubs have very little in common. There needs to be a way to limit the number of clubs a person can join, or to restrict who can join a particular club based on geographic or activity parameters.