Are you sure?
That is not what the T&Cs say.
There are better earning rates available on certain cards in certain situations (Amex Explorer etc etc) but for a fee free cc (if lucky enough) then it does offer value where Amex use is surcharged
Latest T&Cs for fee-free for life Citi Platinum Signature have the following ratios...
2 Rewards Points per $1 for selected purchases made and booked directly from a range of major restaurants and restaurant chains, major hotel chains and flights directly booked with major airlines and international spend
1.5 Rewards points per $1 for selected purchases made at major petrol outlets, major supermarkets and major national retailers
1 Reward Point per $1 spent everywhere else on Eligible Transactions
So as in the case where you bulk buy supermarket egcs and convert into other gcs then:
Earn rate = 1.5 Citi Reward points per dollar spent (other than Govt related) and convert at 2 CR = 1 VFF become
0.75 VFF per dollar spent
or if spent on major airlines related or dining =
1 VFF per $1 spent
Point Hacks has a useful summary (which I unashamedly C&P).
Guide to Citi Rewards credit card points program - Point Hacks Review