You don't need frameworks or bundlers for simple cases. For many you need just one .html file.
For e.g. Android you need quite a bunch of files and directory structures to do even get a Hello world [1]. You need to compile and bundle and package. And install. And god knows what if you want the application distributed. And then you have to fight with the inconsistent and very boilerplatey Android APIs. And figure out which API was deprecated yesterday and what's today's one that will be deprecated tomorrow.
From what I gather, iOS native is even worse. E.g. have to buy a Mac and use MacOS. And Xcode. And faff with signing keys.