The game mechanics require 2 colors that each contain 2 suits. Playing cards fits this requirement, are widely available, and importantly everyone knows what the suits/colors are. The same isn't true if you used random companies or game characters.

Which is a good message that this type of role / career is not good for you. The excitement is in the winning, does not matter what is being traded as long as you win.

lol hyperbole much.

What’s the hyperbole? This is partly a recruiting tool. If you think the game is not exciting then this is probably not the career for you. Do you have something more substantive than a weak attack?