They already are – there's a system webview on Windows and macOS. There are a few "Electron alternatives" that use the system webview instead of bundling a copy of Chromium. Tauri [0] is one of them, built around Rust, and it's pretty great. I built a video editor with it.
The usual complaint against this is that you have to support multiple browsers (Edge/Chromium on Windows, Safari on Mac).
Are those services or just shared libraries? I would imagine, although I'm not sure this is the case, that 50 tabs in a browser consume fewer resources than 50 individual WebViews.
