The new approaches to HTML/CSS run directly counter to the specs sometimes.

Take Bulma for example. They provide styles for titles and subtitles, but their examples use h1 elements.

See: https://bulma.io/documentation/elements/title/

Why is that a problem?

This is explicitly addressed in the HTML 5.2 specification.

> h1–h6 elements must not be used to markup subheadings, subtitles, alternative titles and taglines unless intended to be the heading for a new section or subsection.

See: https://www.w3.org/TR/html52/sections.html#headings-and-sect...

As the author suggests, they don't understand the tools they're using.