fephisto
I used to think like you until I tried the OCC at Regent level.
Every time I have played it I have never had more than 2 resources and usually had only one.
I found it not too difficult to get all the resources I needed thru trade.
I also discovered that you do not need a resource to complete a unit or improvement only to start it.
In other non-OCC games I have sometimes been without a vital resource say saltpetre. If this is the case I would trade for it,
make all my upgrades and start producing many calvalry and musketmen and then let the trade lapse after 20 turns.
I have also taken a far off city which had oil, created a new city near by with a settler brought over for the purpose, immediately built a harbour in the new city with cash , started building infantry in most of my home contient cities and then lost the far off cities and their oil.