It's cool. Just got off work so I can go into greater nitty gritty now.

To break down why this one item is worth war over but a race of monsters could kinda mass produce it you have to get into a small amount of broken ass DnD economics. For the most part economics doesn't exist in DnD, but it kinda applies.

The average farmer earns 6-10 gold a month in DnD3.5. Much less in earlier editions. But that's kinda where I set my minimum wage for someone working full time and being able to feed themselves. The Decanter of Endless Water costs 9000 gold to buy outright or nine weeks and 4500 gold to make it. So if 1 gold equals roughly $100US; They essentially on the off hand gave this one small village of 100 or so people a $900000 gift. A gift that means unlimited water to drink, grow crops with if they find soil, etc. Needless to say people are willing to kill for water that doesn't need to be desalinated and comes out of a 2lb container endlessly.

Aboleth(Yeah, I misspelled that sucker a lot above) are a sea based race of 3 ton evil psychic eels that commonly enslave most things around them, have been around since the gods were young and possess genetic memory. They can be BAMFs in the right GM hands.

Normally people see them as conquerors only limited by their lack of feet and thumbs. Also they breed hella slow. So they have an empire of wealth and the ability to steal a kings ransom if they need more. But being the smartest thing around and older than gods means usually they're addicted to complicated schemes like rituals to flood the earth or make it rain forever. it wasn't until it smacked them in the face that they realized the mortals had an easy way to flood their own world, a bet slowly. Capture a few Artificers or Wizards, enslave them, have them craft it. Or just use a thrall to buy a bunch of them from around the world.