Merchant Firms and Overall Goals for Them

Hello,

Is the goal for a small or medium merchant firm to go upstream? If so, why don't all small to medium firms have upstream assets?

I understand the hurdle for energies and metals might be capital and regulations, but what about ag? I am not sure how easy it is to acquire farmland, but it can't be as difficult as buying a mine or well? Or am I mistaken?

Thanks!