The point being in the Oil & Gas Industry, there are many critical pieces of equipment that depend on adequate mechanical, metallurgical, chemical and physical properties in order to operate properly and reliably.
ISO 9001, AS9100, API Q1, etc are QMS standards and don't delve into product performance requirements for obvious reasons
The point of linking the API document was to clarify that, even from API's perspective, proper heat treatment of critical products is paramount and many failures have been attributed to that issue.
A QMS that does not address product requirements in a robust manner is obviously a QMS that does not add value. We have to go beyond the general requirements of QMS standards in order to assure product integrity and fitness for use.
All this is true.
Would this also be driven by customer requirements? And if so, how many machine shops or heat treat shops would perform destructive testing at their own expense?