One of the standard peices of equipment for an adventurer is a sword. But swords were actually very complicated to manufacture. Therefore, an adventurer who owned a sword might have had it passed down through the generations or might have been rewarded by some influential figure. Or simply looted it from a tomb.
What if potions and tonics had negative side effects? Potions of increased strength cause violent tempers, or damage joints. What if potions of dexterity caused tremors, or palsy?
What if they were addictive, and had withdrawal symptoms?
Could someone make a bad batch? No one use the brown strength potion!