[CONAN] Question about Commoners

[Supplement Four]

Look at page 94 of Tito's Trading Post. There, it shows sample Argossean Merchants.

Note what it says in that first paragraph:

Commoner is not a favored class of Argosseans, so their skills and feats are affected by this simple change.

Checking, I see that Commoner is not a favored class of ANY race in the game.

What do you think that line above is referencing?