Only certain ideas (production methods implemented in shops or factories, for example) could be hoarded. Other ideas had to be disseminated in order to create economic value from them, like the classic example of a "better mousetrap." There's no way to sell a better mousetrap without revealing how it traps mice. Anyone who buys one can disassemble it and then build their own.

Without patents, small inventors are defenseless against bigger organizations, which can replicate the invention, manufacture it faster, and put more marketing dollars behind it.

Patent protection, like many federal laws, is a balance. On one side, it does not allow the replication of inventions without permission of the inventor, to protect small inventors. On the other side, as you mention, it requires public disclosure of the invention, so that method inventions that would normally be secret forever can eventually be used by the public.