Exactly. A website or web app can be updated as often as you want and you can be certain all your users will be seeing the latest version. Native apps have a different release cycle which brings unique challenges. SDUI is an approach to bring some of the benefits that web apps have to native. Of course you could just embed a web view in your app but then you lose out on a lot of things that make native great.

Let me tell you about mainframes and dumb terminals.

now that I have the snark out of me - having a mobile app just be a web view that serves up a nextjs site or some such - which can then be used to power your website too ... is definitely a good idea now for many apps ...