I wouldn't go that far - it's a good starting point, as is having a straight leg with heel on the pedal in lowest position. I believe that the truth is that there's not a universally optimum position for any rider, but there may be a position that suits a rider better than other positions overall. Sprinting on the drops downhill is an entirely different scenario to a leisurely fully-loaded tour on the uphill. A saddle position could be correctly set up in relation to the pedals and balance by being low and set back or higher and more forward but one might be preferred over the other due to reach and handlebar design or for other reasons.Kops is another myth that needs to be put to bed . . .
There's a guide by a bloke who resides in a neighbouring parish of this forum. He's not a bike fitter but has designed bike frames. Imho, I think it is an excellent guide and anyone asking questions about bike-fit, my advice would be to read that guide.
Here's the link to it:
http://wheel-easy.org.uk/wp-content/uploads/bike-set-up-2017a.pdf