What does javascript have to do with e-commerce? It's not even an essential part of the web. I used noscript for years and only stopped because developers got lazy and stopped doing things properly. Unprecedented quality of life thanks to javascript? Get a grip. It's not even an easy language to learn.
To explain it differently: UX is all about minor details that can be the entire difference between a github repo with one star from a buddy and an IPO with fuck you money for everyone involved. So things like "why does the website have to reload completely" are a no-brainer, Javascript is a must.
Unprecedented quality of life leaps were possible because of 100% user experience focused websites. The user wants popup menus and other interactive elements, they are objectively, measurably better (check out any UX research website). And Javascript is the way to enable all of that functionality.
