That’s true, but it’s not like translating HTML into a bitmap for a display is some spontaneous process that happens for free. Your browser is anyone going to interpret all that HTML and CSS, and your users are going to click on buttons and submit forms that require changing that HTML and CSS. Whether that happens through JavaScript or SSR is bike-shedding: processing will be done, computation is needed, we can sit here and argue about how the web front end world sucks but billions of users expect interactive web applications that are very difficult to deliver without JavaScript.