On the other hand, if there are a lot of students deferring, there is a huge line behind them willing (and able!) to get into Harvard. Harvard and other elite institutions will not suffer for students for quite a while.
If you want to take a year off you can come right back the next year if you've already been admitted. I'm not sure what incoming freshman are thinking, but for current students, why the hell would you not take a year off?
If anything, I'd think the choice of incoming freshman is even clearer assuming they can defer--including financial arrangements. I'm sure they could find something better to do than severely compromised campus activities that might revert to full-on remote a month into the fall term.