As others have maybe hinted at, statistically, there actually isn’t grade deflation at Vanderbilt. Many of Vandy’s peers in the top 20 are known for inflating grades, and many Vandy students realize they probably could have received higher grades if they went to their state flagship. That said, the average GPA/grade distribution at Vanderbilt is certainly not deflated compared to all other private universities.
The tough thing about bringing in 1600 students who were all at the top of their highschools is that 90% of them aren’t going to be in the top 10% anymore. Some top schools choose to inflate grades to make this less emotionally challenging for students, but most academics consider that unethical, and Vanderbilt chooses not to participate in that game.