This is true for static layouts. However I think the compelling use case is when the font weight changes dynamically such as on hover or focus. In this case it

This is true for static layouts. However I think the compelling use case is when the font weight changes dynamically such as on hover or focus. In this case it can be useful to avoid having the layout shift (especially on hover where the shift risks moving the hover target and creating an unwinnable game of cat and mouse).