Comment by ushiroda80

I don't think reasoning needs to be that complex. Addictive things are harmful, social media is design to be addictive (and is increasing). There is a correlation of higher addictiveness with harm. Children in particular are vulnerable for addictive things. So given the above, the expectation for social media which is highly addictive is that it would be highly harmful, unless there are clear reasons that it's not harmful.