This takes me back to when the goal of a webpage was to be less than 1Mb. At the time, the only reason to use PNG (such luxury) was when you needed transparency

This takes me back to when the goal of a webpage was to be less than 1Mb. At the time, the only reason to use PNG (such luxury) was when you needed transparency. The variable compression of JPEG was very important. In Photoshop you could just grab an image and choose the file size you needed and the JPEG quality would degrade to match your design constraints.