Is the Alchemy skill incomplete?

I thought that Alchemy was structured somewhat like healing, identifying poisons vs identifying disease, but while the 3 ranks of healing give you various abilities, it seems all alchemy gives is better identification, then only at 3rd rank do you get to craft potions.

What does having rank 2 alchemy give above having rank 1?

With two ranks you can act as an alchemical assistant, which means you can assist in potion creation (p. 119)