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).