Social features do not make a social network. Maybe it’s just where I cycle (Northeast and Northwest USA) but approximately 100% of the people that I ride with post their rides to Strava. That is what makes it a social network.
Further, all of the alternatives that you listed have limitations that prevent them from being viable alternatives to Strava even if people were interested in migrating. Mainly these are related to device integration.
There are many alternatives for tracking and analyzing performance data, but I’d posit that that’s not what most Strava users do there. For most of them, it’s a social network, and that’s it’s focus as it goes public. There’s no alternative “athlete focused” social network that allows planning and organizing group activities, has tight integration of activity info (e.g. tracking that the group bike ride averaged 20mph over this route, or that person X and I competed in the same park run, and here’s the finishing time for each of us, along with a few photos and some performance data like pace and heart rate).
Because of investor pressure to generate actual meaningful revenue, Strava is going to rapidly enshittify leading up to their IPO and after it. The unfortunate thing is that they’ll largely get away with it, because there’s really no alternative for users to move to.
Very basically, what’s happening is that every file that is read (including the binaries and libraries that make up the services you run, etc) is loaded into memory and stays there until that memory needs to be reclaimed for something else. It’s a good thing. It means that the next time that file is needed, it can be accessed directly in RAM rather than reaching out to the filesystem.