The monadic chaining section makes no mention of for-yield strangely enough. Their example

    def getAddress(name: String): Option[String] = {
      database.get(name).flatMap { elem =>
        elem.data.get("address")
          .flatMap(Option.apply)  // handle null value
      }
    }

could just be

    def getAddress(name: String): Option[String] = {
      for {
        elem <- database.get(name)
        address <- elem.data.get("address")
      } yield address
    }

and it's way more readable than their given rewrite.

Then again, for-yield might be too magical and "can confuse programmers less familiar with Scala," which seems to be a reason for a lot of the stylistic decisions.