[selectors] Why is :matches() restricting pseudo-elements?

Hi,

The definition of :matches() has the following restriction: "Pseudo-elements cannot be represented by the matches-any pseudo-class; they are not valid within :matches().”.

Can someone shed some light this restriction?

Greping through some CSS, it seems quite common to have “something::after, something::before”, which could be written as "something:matches(::after, ::before)”. This seems like a useful capability.

Benjamin