By POH I assume you are talking of the flight manual . Folowing Lu's logic operating the aircraft over gross weight is OK because the baggage compartment is large enough to take 10 cu ft of depleted uranium .
To suggest that you cannot change the flight manual based on service experience is patently absurd . In a perfect world the flight test program and design review would find every possible fault that might occur. I think that flight manuals carved in stone may be a little overkill not to mention overweight. Can you give a single example of an in service helicopter where the Flight Manual is still at Revision A ?. ( unless you forgot to sign up for revision service ).