My ideal web browser should be able to identify if a page really needs JavaScript enabled or not, and disables it if all the page does with JavaScript is load Facebook/Google/Twitter's iframes, advertisements, shows animations and popups etc. which have nothing to do with the content. Disables all autoplaying content, doesn't load images like large banners and footers automatically.

Kinda like switching to that "Reader mode" of Firefox automatically based on some AI.