Web Components are great for distributing UI elements that work with every framework.
Web Components are terrible for just building apps. Use a framework!
From this perspective, Elena seems like a welcome approach. If Web Components are for library authors, and they are, then it stands to reason that Web Component frameworks optimize for that as well.
It's lighter then a framework, events are vanilla JavaScript so you don't have to figure out how to make a JS libray you've found work within some framework's custom event bus.
It has enough rendering support so you don't need to update everything with .innerHTML. Change the state of a component, lit will call your render function but only update the parts of the DOM that have changed. I felt that was a nice partial answer to suggestions you need a virtual DOM because updating the real DOM is slow.
And then most library developers find them severely lacking, riddled with unsolved and unsolvable issues, filled to the brim with invalid assumptions and awkward APIs etc :)
They are somewhat okay as framework-agnostic "leaf" components if the authors spent a lot of time honing the usage and the APIs. Things like date pickers for example.