Why do schools "admit deny?"

Years ago my D applied EA to a pricy private school. This was before NPCs were standard. She was deferred to RD. She was accepted RD but the letter said something to the effect of “we are unable to offer you any financial aid.” My interpretation was, if you really want to come and are willing to pay full freight we’ll happily take your money, but otherwise forget it, we’re not that interested in you.