Mitosis is inspired by many modern frameworks. You'll see components look like React components and use React-like hooks, but have simple mutable state like Vue, use a static form of JSX like Solid, compile away like Svelte, and uses a simple, prescriptive structure like Angular.
Managing support for libraries that provide UI components across frameworks is a pain, especially when webcomponents are not an option (e.g. for server side rendering, best performance, etc). With Mitosis you can write once, and run everywhere while maintaining full compatibilty with the target framework.
Mitosis allows you to incrementally adopt modern and familiar workflows for many different platforms. For instance, when working with Shopify, you can server side render to liquid and hydrate with React.
If you have ever had to migrate a huge codebase from one framework to another, it's an absolute nightmare. Writing components at a higher level of abstraction allows you to move from one to another with ease.