I've been hearing this for a decade; nothing changes. Guess why? After all, even in a small application larger than a single page, the biggest complexity comes from data flows, control flows, passing back and forth, and manipulating state fragments. And dependencies. And derivative states, locals and globals.

Web components don't solve any of this, in fact, they add additional - unnecessary - complexity because they are not native 1st class citizens to frameworks. It's funny, but UI and isolation, where Web components shine (even that I doubt it), is only 20% of the work. Sometimes <5%, especially if your framework already has its own UI Kits, and it has, such as Material or AntD or SvelteKit, thousands of them.

For small "widgets" - yes, a good choice. For applications - first time I've used Polymer in 2015...