Lifting, twisting, turning, etc heavy things isn’t intrinsically bad, but it is intrinsicallyr risky. In a gym environment you have the ability to control that risk.

As a lifter you have full control over how many reps you do, you have all the time in the world to make sure your form is good before lifting, you don’t need to move around while carrying that weight, and you’re lifting conveniently-shaped weights.

Also, even the most well-maintained mechanical device will eventually suffer from material fatigue when put under load for significant amounts of time. Our bodies are no different.