So much of this is because of the mobile "app" craze where -- due to the limitations of mobile app architecture, you had to build a stateful "app" instead of several independent screens with some limited shared state (usually just a token).

Native mobile UIs are great, but something as simple as cookies / local storage could allow for stateless (or at least less stateful) mobile apps with native UIs.

Now, the abomination of hybrid (cordova), or pre-processed (react native/xamarin) mobile apps is whole other thing, but often why web apps are translated to SPAs.

If we need a mobile app as well, why not use a common code base for web and mobile...