Why strength scales with cross-section, not bodyweight
A muscle's maximal force is broadly proportional to its physiological cross-sectional area, which scales with the square of a linear dimension, while bodyweight scales roughly with the cube. As athletes get bigger, absolute strength tends to rise but strength relative to bodyweight tends to fall. This is why the strongest absolute lifters are usually the heaviest, yet the best pound-for-pound lifters are often lighter.
The diagram contrasts these two scaling relationships, showing why a single heaviest lift does not crown the most efficient athlete.
How weight classes and allometric scoring balance it
Powerlifting weight classes exist precisely because of this geometry: grouping by bodyweight keeps competition fair. Scoring formulas such as Wilks or the IPF points system apply an allometric correction so a 60 kg and a 120 kg lifter can be compared on relative terms.
This is general educational information about competition structure and biomechanics, not training or medical advice. Individual strength is also shaped by limb lengths, training history, and technique, so the curve describes a population trend rather than any one athlete's ceiling.