I'm a web dev and yes they could. It's annoying that web devs get blamed for it though, the reason for all the javascript is mostly business decisions out of our control.
Mainly the tracking scripts which the marketing department adds against out will. But also it's a lot cheaper to have a client-rendered web app than a traditional website (with client side rendering you can shut off all your web servers and just keep the api servers, our server side processing went down 90% in the switchover). And it's more efficient for the company to have one team working in one programming language and one framework that can run the backend and frontend, so the frontend ends being a web app even if it's not really necessary.
Sorry but I'm on the mod's side here. Some content doesn't belong on some communities. Most people upvote from their front page without even checking what community you posted to. If you allow things based on popularity, every community devolves into deep-fried shitposts