I was forced to use this years ago because there is only a :nth-of-type selector, but no :nth-of-class. So whenever you need nth-of-class, switch to made-up tags and use nth-of-type. (A tag is a type.)
IMHO this also makes custom tags no longer very useful beyond custom HTML components (JS is also required for that). The standard tags provide good semantics, SEO and accessibility out of the box.
