My post was made before 1.9 prerelease 4, or before grenades. I did not say that you cannot make poison, instant damageharming, weakness, fire resistance, instant health, swiftness, slowness, regeneration, or strength (well, maybe regeneration, but THIS WAS BEFORE PRE4) potions. These are the only effects you can gain from potions AS OF PRERELEASE 4.
EDIT: I meant from potions, not without hacks. Hunger is possible without hacks.
All these potions continue the "self-made jobs/classes" thing that's been happening ever since 1.8. For instance, people with patience and will to explore become Raiders, locating abandoned mineshafts and other structures, finding treasure, and returning it to the surface to trade it with merchants or other people in need of small amounts of stuff, or they will become miners, returning with efftons of iron, redstone and coal, plus some diamond and a GINORMOUS amount of cobblestone to give to Crafters, Builders, Redstone technicians, and others needing supplies. Then there are the self-dependant Rogues, the Woodcutters, the Hunters bringing in stuff from mob drops such as Blaze Powder, Slimeballs, and gunpowder, etc etc etc.... And the Potionmasters, buying from the Miners and Hunters and staying indoors making potions and doing a bit of Enchantment on Stone tools, perhaps, if they get bored.