Sharks don’t need arms either. They just swim up and take a bite. If T-Rex had any kind of sprinting ability it would have made for an ambush predator against very large herbivores. But as with most meat-eaters they swing between predator and scavenger.
“If T-Rex had any kind of sprinting ability...”
One scientists I read said he did, wrote that T-Rex was a roadrunner from hell.