DarkSaint85
Bonified abstract
Way I saw it, yes, the Hulk has limitless anger and thus, limitless strength.
But he needs to be able to get that angry. THAT is the valve, the limiting factor, on him.
We argue in character. Not just a powerset. What makes Peter Parker angry, for example, wouldn't make Banner angry, and vice-versa.
Therefore, in order to really take full advantage of his limitless anger, you need external stimuli to get him angry - and keep adding it on.
Losing his wife and unborn child, his entire home, thanks to his 'friend', being a massive dick to his other friends as a result of it, being able to finally cut loose without fear of killing someone, THE Betty kissing Tyrannus etc - all those factors piled on top of each other gave us the World Breaker.
And he was explicitly said to be the angriest he had ever been. Multiple times.
Could he have gotten angrier? Well, there's no cap on it - perhaps if it turned out his mother was resurrected in front of him then tortured, and he found out about Tony messing with the gamma test etc etc at the same time, he might have gotten angrier - but with no such factors present, he cannot get any angrier.