This is not a mozilla invention. The only thing Mozilla should be ciriticzed for is that they are the last implementing this. All other browsers already support

This is not a mozilla invention. The only thing Mozilla should be ciriticzed for is that they are the last implementing this. All other browsers already support this header. It's a bad situation, but it's based on bad decisions that were made in the 90s when the web was in its early days ("be liberal what you accept"). Hard to fix in a general way without breaking lots of stuff.