Thanks for your comment, I'll cover this angle. Of course, none of those factors can be influenced by the site itself, and all of those factors influence all s

Thanks for your comment, I'll cover this angle. Of course, none of those factors can be influenced by the site itself, and all of those factors influence all sites at the same time. We're focusing on things we can improve. Although it's a simplification, I believe it's broadly correct to categorize things this way. The main reason to highlight this is because oftentimes people (clients) will focus too much on the "heavy page" part, because that is what measurement tools like Google PageSpeed Insights mostly tell you to improve.