This is sort of an aside based on something I read in the article but does anyone know why the RFC guidelines say that you should first send an informational GO

This is sort of an aside based on something I read in the article but does anyone know why the RFC guidelines say that you should first send an informational GOAWAY that does not prevent opening new streams when gracefully closing a connection? They point out in the article that it's a better practice to immediately limit stream creation when you detect abuse - not wait for a round trip to complete first. I'm sure there's a good reason for the original guidelines; I'm just trying to get it and haven't found anything clarifying through Google. Was it specified before the rise of modern attacks?