I've heard that argument many times and all it does is reinforce the idea that no other implementation can work. And how you end-up with an implementation mono-culture. Forks of a single block happen regularly, it can be dealt with. A production system can detect a fork and check the reference implementation's behavior, preventing any longer fork.

The *coin ecosystem need more than one implementation, a single codebase can't cater to all uses. I should know, I'm an Apache member.