I'd say that it depends on what you're building and if you work in a team - there's so many components that would require a lot of work to create in vanilla if used together in the same app.

Like menus, wysiwyg, tables (sorting, search, pagination), tabs, photo viewers, modular windows, accordions, form builder, notifications, cards, process sliders, color picker, ratings, spinners, stepper, uploader.

Then binding all of that together.