If humans can't govern themselves then what hope do they have to govern others?
If doctors can't treat themselves then what hope to they have to treat others?
If (most) humans can't build passenger aircraft what hope to they have to let others build aircraft for them?
see the flaw?
Another problem with this is, if a doctor or an airplane maker screws up, I can abandon them and go for a replacement immediately. With politicians I'm pretty much stuck until the ignorant masses change their minds.