I agree with this. Media queries are a tool that eliminates the need to maintain separate HTML templates for mobile- or tablet-specific versions of a website. They work well at this task.

Element queries as described by the author address an entirely different set of concerns, which is that modular components of HTML might be re-used in varying situations, and depending on the implementation you might want to style them differently. Media queries are the wrong tool to solve this problem.

The problem is that when we want to use this:

  .testimonial (max-width:27em) {font-size: 0.8em;}

We have to use a context-specific style definition instead:

  .testimonial {font-size: 1em;}
  .signup .testimonial {font-size: 0.8em;}

Or, better (from the parent):

  .testimonial.vertical {font-size: 0.8em;}
  .testimonial.horizontal {font-size: 1em;}

You might still have to revisit each of these styles in a media query to apply changes depending on the global presentation. So while the proposed element query might eliminate the need to chain selectors, I do not believe that it simplifies media queries in any meaningful way.