The term "lifecycle" in web components has a completely different meaning compared to its use in vdom implementations. Compare the semantics of "lifecycle" events in web components against React: https://reactjs.org/docs/react-component.html

They have virtually nothing in common. Web components are essentially just new DOM events, albeit more restricted.

I started this thread by mentioning Surplus, which has no lifecycles because it operates directly on the DOM, and so React's lifecycle callbacks have no use.