An applicant like the OP (perfect ACT, highest weighted GPA possible, good ECs, and I am assuming positive recommendations - combined with legacy status and a separate application for merit scholarships) should be a near shoe-in at WashU. Flukes happen, but if were OP I would be very confident. Building on the comments of @mamaedefamilia, I have a theory that WashU might use its merit scholarship program applications to weed out Ivy-hopefuls that aren’t really interested in the school. That is, if you are a top candidate that is serious about WashU (even if it wasn’t necessarily your first choice), you would have taken the time to make yourself aware of these scholarships, to know that you would be a candidate for them and apply for them. I think this is much more so at WashU since (a) it doesn’t require a supplemental essay (they are the only highly competitive school that I know of that doesn’t), and (b) I believe all of its merit scholarship programs require a separate application (not the case at many other schools).
I don’t know what WashU’s legacy policy is, but other schools are pretty clear in stating that they don’t take into account the legacy status if the student applied RD, since if you’re not going to show them the love, they are not going to show it back. My D1 had lower but similar stats to the OP, and did not apply to one of my alma maters Duke until RD, and she was waitlisted. (Also, waitlisted to WashU, but that’s another story). For the schools that take demonstrated interest into account, not applying to them ED or EA can be risky no matter how good you look on paper.
@lostaccount I see what you do. you jump from thread to thread and post inaccurate claims about schools and than when challenged you post on other threads. most recently you posted a similar inaccurate claim on the Wash.Univer.scholarship thread about the school. Wondering what grudge you have to bear on this school and others. please stop posting inaccurate claims that can’t be backed up!.
OP, I think you’re good lol. The only thing that I can think of that could screw it up is if you came off as a complete tool or robot in your application. I’m sure you didn’t. Even if you get rejected, based on your stats, you’ll get in somewhere great.
Good luck!