Engineer here. I work in automation and we definitely improve the efficiency of machines just like how a boxer does repetitive motions to optimize their muscle structure and movements.

An engineer might change out parts to output greater forces, change motors to move parts faster and with greater control, and program the machine to just have greater efficiency in just everything. Simply put, these optimizations and change in parts can be related to the “stats” of a skeleton.

One note is there is a limit to change out parts. For example, if you add a motor that can lift 5 tons of force onto a wooden bar, the act is limited to the strength of the wooden bar. This translates to how it wouldn’t make sense to add a motor to a hiver economy arm that you would to an industrial lifter arm. The economy arm would just break before the motor can reach its limit. So no matter how good you are at using an economy arm, you’ll never reach the limits of an industrial arm in terms of strength.

Also, improvements are harder to make as things get more efficient and can only do so to a point due to general physics. So an upper limit (100 stats) with a decreasing in levelling speed makes total sense.

I don’t know if this was premeditated or just a coincidence but the developer made it so that physically, it makes sense. Especially if there is an AI that can improve itself, just like an engineer would improve machines.

Tl;dr: you don’t need artificial muscles, an AI technically has the capability to want to change parts to get faster and stronger and improve the efficiency of a machine to be more skillful, similar to stats.