No, there is no such requirement that I am aware off.
However, SPMs have been used in relatively mild areas such as West Africa and around the world to transfer product to/from onshore and offshore production and storage facilities. Connecting to a SPM is a standard operation with tug assistance, station-keeping is easier to manage since the tanker has the ability to freely weathervane. An SPM can be located remotely from the FPSO (about a mile) therefore increasing the distance from the tanker in comparison to side by side and tandem operations and resulting in less tanker FPSO interaction.
The main concern with SPMs is the relatively high CAPEX. The technical issues are greater in deep waters: the mooring line footprint will have to suit the subsea field layout. At the time of the study the export lines and their connection to the buoy were raising new design issues, particularly regarding fatigue in the case of steel lines. Since that time the technological gaps for deepwater CALM appear to have been solved.