I am actually quite surprised Terence Tao still gets papers rejected from math journals... but appreciate him sharing this, as hearing this from him will help newer scientists not get discouraged by a rejection.
I had the lucky opportunity to do a postdoc with one of the most famous people in my field, and I was shocked how much difference the name did make- I never had a paper rejection from top tier journals submitting with him as the corresponding author. I am fairly certain the editors would have rejected my work for not being fundamentally on an interesting enough topic to them, if not for the name. The fact that a big name is interested in something, alone can make it a "high impact subject."