That sounds like yield enhancement, i.e., trying to decrease the denominator in the ratio of students matriculating/students accepted. I don't follow USN&WR rankings at all, but others on college confidential have said that USN&WR no longer uses this measure. But the sense on that website was that multiple schools were doing this.
I don't see yield enhancement strategies as anywhere near as disgraceful as the counting requests for information as completed applications, which is what washu was accused of doing earlier in this thread. Yield enhancement through strategic declines has significant risks for the school ... they could lose otherwise highly desirable students. Plus, if word gets out, highly desirable students may be less likely to apply there. It's somewhat self-correcting, or at least, self-limiting. Lying about how selective you are has no direct downside.
WashU has long had a reputation for having taken shortcuts to achieve selectivity ... in the end, salting the applicant pool with kids they knew they'd never take becomes a self-fulfilling prophecy, for the low accept % attracts more top students, which then allows for more true selectivity, etc. They now attract a very selective group of students, unless they're lying about their students' average ACT/SAT, class rank, etc.
Those interested in alternative, objective rating systems might google the "revealed preference ranking" paper by Caroline Hoxby, et al. This paper demonstrates a ranking system based on applicant preferences when dealing with multiple acceptances. For instance, a student accepted to Duke, Yale, and Stanford who chooses Duke gets coded as a win (1) for Duke and a loss (0) for Yale and Stanford. The method implicitly takes into account financial aid packages, merit or need, which can sometimes make a full ride at Vandy, for example, look more appealing to some than paying full freight at say Cornell or Duke. So it's an interesting ranking, kind of the ultimate popularity contest for colleges, but does not rely on gamesmanship or "peer reputation" and other things that can be easily manipulated.