Strava could easily make this opt in, or they could filter spots where there are only a few people using it. There are a ton of in between options, this data is not a yes or no scenario.
Either way, there's a very clear route that leaves the road at my house and follows my driveway. It doesn't take much effort to find many, many more examples of this throughout the heatmap.
I don't think I have strong feelings about it. I can see the point of something as severe as a data protection law that would require the app to explicitly ask for permission to share every activity (with options like "store to cloud" and "store to cloud, share data publicly"). On the other hand I'm not really bothered by the "don't use Strava" method of opting out of their data collection.