Is that a emperically testet hypothesis. That Powerlifters are more intelligent than Bodybuilders or is it just your own observation.
Its a general conclusion, and i've only seen it confirmed in person.
The knowledge required become a good bodybuilder, when having the genetics for it, is fairly basic. You ask someone to calculate your calories once, work out a standard diet on 2.5-3.5g protein/kg , 60 grams fat and get the rest of the kcal from slow carbs. Most steroid cycles are tailored towards you, and pretty much everything improves what you'll be doing. the rules are small and simple. You work from the 2 day split 4 day schedule based on easy to execute isolated excercises, and the key to succes, is your ability to stick rigerously to your diet.
The training routines change in added sets and variations, and increasing number or reps.
It requires much, much more knowledge to become good as a powerlifter. You need to learn your lifts and build core muscle. Improve your compound lifts while evaluating the state of your larger muscles. The key to succes is your training and the ability to detect flaws and how you'll target them besides following a training routine thats allready build around the speed you can recover on.
The issue of balancing increase in muscle, tendon and CNS strength is difficult on its own naturally, its a complete nightmare when finding a roid cycle for that.
First you get weight class issues. Then you have recovery issues as steroids greatly enhance muscle recovery, but much less tendon and CNS recovery, and the posterior chain that needs to be balanced out despite quadriceps for example that do recover quickly.
Because of this, only a select few types of roids come into consideration, and there is a massive importance in the post cycle recovery, infinitly more compared to posing sports.