Bing Chat is built entirely with Web Components.
(I work at Microsoft on it. You can verify with F12.)
(I work at Microsoft on it. You can verify with F12.)
Reddit doesn't seem to use web components at all? https://imgur.com/a/kzLoGnV
Youtube seems to use 1 web component for every 10 normal components, which is fair: https://imgur.com/a/YIBhLh8
Reddit doesn't use web component on all pages yet. They have them on certain types of comment pages now and are incrementally porting the rest of their site from React to web components with Lit. They've also built this year's r/place with Lit, and are building other things like embeds on web components.