This morning I got an
email from United saying that I could redeem frequent flyer miles for
e-certificates (discounts on flights).  

I can redeem 1,000 miles for a $25 certificate or 5,000 miles for a $75 certificate. The United
website has the same offer. 

After poking around to
find the terms and conditions, and then reading all the fine print, I found the
last bullet on the list of terms: 

Other
Important Notes:
Multiple electronic certificates may be redeemed using miles, but may not be
combined on a single reservation. Maximum number of passengers per reservation booked
using an electronic certificate: 1. Only one discount
certificate, discount voucher or promotional discount may be used per ticket. 

OK– so my first thought is
not possible. I can’t get 3 – $25
certificates for 3,000 miles and use them on one flight. 

I just don’t
understand why they are penalizing me for wanting to acquire a more valuable
e-certificate.

I would think it would be
more logical to offer some benefit for trading up (i.e., 2,000 miles for a $25
certificate and 5,000 for $75). 

What am I missing?