The mod_pagespeed filter "prioritize_critical_css" was released exactly 12 years ago in early May 2013. At least 3 more popular critical css tools were released

The mod_pagespeed filter "prioritize_critical_css" was released exactly 12 years ago in early May 2013. At least 3 more popular critical css tools were released the following year, integrating with Grunt, Gulp, and later Webpack.