the moment that ideas are made public with consent, they should be considered public domain

But that's the inventor's choice, right? Patents incentivize publishing inventions: you make your invention public in exchange for exclusivity for 20 years or so.

The other choice they have is to keep it a trade secret, which is kept private for as long as you choose, but you don't get any exclusivity if someone else comes along and invents the same thing on their own.

By creating a system of laws where publication gets rewarded, we encourage those people in that industry to freely publish rather than guarding their secrets to die with them.