Pattern matching - why is it implemented at the language level?

gistfile1.scala

object Any {
  implicit def matching[A](a: A): Matchable[A] = new Matchable(a)

  sealed class Matchable[A](o: A) {
    // "match" is a reserved word, so lets call it "matchIt" instead
    def matchIt[B](pf: PartialFunction[A, B]): B = {
      if(pf.isDefinedAt(o)) {
        pf(o)
      } else {
        throw new MatchError("...")
      }
    }
  }
}