I belong to a car forum and we often post links to online sales of vehicles so that our members can have all the help available in finding that perfect project or daily driver. For example, "I was surfing the XYZ car auction site and saw a 1932 Blockenschlugel convertible for sale for $12. Somebody should jump on this amazing deal." Why are we not allowed to post similarly here? Does it have to do with ATF regulations or are we just trying to avoid any potential perceived firearms trafficing misconduct?