I can speak to this idea a little bit …
I’m on a dev team for an app written in Flutter, and the most experienced member of our team complains a lot any time we have to resort to using webviews (which is what you’re referencing).
While webviews are nice because you can use HTML and javascript (and hence use packages that already exist in javascript), the price you pay is in performance. You get “janky” scrolling and slower performance overall. A scrolling-intensive app like a Twitter clone would really suck if you did this.