Now if you have X devs in a team you can end up with up to X*2 copies of same knowledge/assumptions. When any such assumption turns out to be wrong you have to change X*2 places, but that's not a problem. Problem is finding all those copies. When system gets large this task goes from easy to impossible.
But I guess it is an OK rule for tiny teams and tiny software systems.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.