You are correct that Strava has a significant social media components, but it also captures data from your rides that tracks progress. If you don't want the social part of it, set your account to private. I'm a social guy, so the social part is valuable to me.

Two years ago, after being off my bike for 15 years, I started doing some indoor trainer work to start rebuilding my fitness. It was dull, and 30-45 minutes was all I could tolerate before being too bored to continue. Then, I learned about Zwift. Zwift is what you make of it. For me, the important component is interaction with other riders in real time, and my usual choice is to join group rides that are appropriate for my level of fitness. However, sometimes I choose to do a structured workout that dictates how long and how hard to go based on what the structure of the workout is, adjusted to my current level of fitness. Other times, I just want to ride at my own pace, as easy or as hard as I want. If you want to race, you can enter a race. If you don't want to race, don't. For me, Zwift continues to be an important part of my riding/training diet.