I can see why you question this rule. Look at the system as supply and load. On the
supply side is the compressor should not exceed 125 psi. All components on the
load side of the system must be rated for at least 125 psi, and the pneumatic lines cannot exceed a certain inside diameter. This guards against over pressurizing the system that can cause burst of a component. I believe you are right in questioning "least" being used for the compressor. I think you should ask the question, quote the rule and emphasize the word "least".
Does this rule mean that we can use a compressor that
exceeds 125 psi?
I don't believe this is their intent, and the main regulator will keep the system below the max pressure. But think what happens if that regulator fails, and the compressor produces higher pressures than the components can handle. Nice catch!
