Bob this is a serious question. What would be the harm in athletes competing in both? i realize it is against the rules but would amending the rules hurt anything?
No harm to the athlete...in a perfect world we would all be able to compete where we wish, etc.
But when you sign the contract to be a part of the IFBB, you sign away your rights to compete in other federations...it's called exclusivity and it's very common in sports and business.
I have an exclusive contract with BB.com that prohibits me from signing with similiar companies. Granted, I'm compensated for that...but it's along the title of "job".
As a sport, the IFBB isn't compensating anyone, but allows it's "members" to compete in their organization and sanctioned shows. If you ndon't like it...no one has a gun to your head to join the iFBB...you can seek other opportunities all you wish, but you can't do both.
It's no different than joining an exclusive golf club...there are rules that must be followed if you want to be a member...you pay to be a member, you don't get paid by the club, and there are times you can golf and times you cant.