While you might be right.

It seems like you didn't notice this was about React Native, the cross platform mobile app framework.

So "just write plain html" isn't a valid alternative unless you want to write a Progressive Web App instead. Which means you:

- Forego the App Store and need to ask users to bookmark your website

- Loose ease of access to device features (cameras, sensors, push notifications)

Ruby on Rails' Hotwire Native is basically augmented "plain HTML", and requires practically zero effort for Android and iPhone support.