Saying "understand that you are here through very little of your own merit" is a recipe for causing already overly stressed students to do something rash, like jumping out of a building: http://web.mit.edu/~sdavies/www/mit-suicides/ (this list isn't even up to date).
Motivating people to work hard to feel like they've earned their place is a completely different thing than reinforcing the doubts and insecurities almost all of them have anyway.
The pressure at this place (and it's the same at any top-tier place) has been almost too much for me to handle sometimes, and that's without foolish words from foolish people designed to increase it.