It's hard to say "Discord just showed why" before the product is in production and sees actual use. Promising initial statistics, but the transition is based on a lot of assumptions that won't really be proven until mass adoption and the software has seen long-term maintenance.
...exactly, and at some point you want to show inline animations or videos and all sorts of other media, show webpage previews, play audio snippets and all the other things things a webpage can do, and then you're back to either integrating a browser engine or attempt to write one from scratch (the browser engine can of course be provided by the system webview, e.g. what Tauri does).