Quote from McNubberson»
What balance is being broken?
It puts people who can afford to keep their computer running at an unfair advantage, negates any drawbacks of fishing (Apart from not being able to do anything while fishing), and makes treasure enchantments too easy to obtain (Just keep the game idling and do something else. Sooner or later you'll get it fo no effort), and generally provides awfully good rewards at the cost of some Redstone, an Iron Trapdoor, some string, and 2 Tripwire Hooks. Consider that even a lowly spawner farm or semi-automatic crop harvester will potentially be more expensive nowhere near as powerful products.