Confusion on what ages an e-girl comes under

Hi, found server on Dishboard, based on topics shown, I never gave thought minors would be able to post Thigh pics, which i commented on 3.  One of which I was informed was underage.  Deleted comment, based on others informing me.  I know it does not say NSFW, so should have been a red flag maybe.  Did some google searches and found e-girl ages could be as high as 20-21.  I apologized and then departed server.  Thoughts..Thanks