You must be thinking of forced IDs, the feature itself is several years old but it's been turned on and off through the years. Something that isn't very well k

You must be thinking of forced IDs, the feature itself is several years old but it's been turned on and off through the years. Something that isn't very well known is that 4chan is actually a lot of smaller communities with only partial overlap, and the culture can differ a lot depending on what board you are. A strangely effective rule of thumb is that the smaller the community is, the friendlier it acts. IDs are only enabled in the bigger and most controversial boards of the site, where people otherwise don't hesitate to abuse their anonymity.