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.
Lifecycles are important if you need to do some arbitrary DOM manipulation upon mounting an element to the DOM tree. For example, you may want to render a google map when navigating to some route.
"Overcomplication" is in the eye of the beholder. You can't tell your client that his wanting a map in the contact page is "overcomplicating a conceptually simple process". At some point, if a system's restrictions are too strict for the sake of simplicity/beauty/etc, then it ceases to be useful in the real world.
Have you tried to build a components library, or have you seen any component libraries that is built on top of a framework that doesn't provide lifecycle hooks for components? Something like https://ant.design/docs/react/introduce or https://developer.microsoft.com/en-us/fabric#/components