but why? It isn't because the aircraft isn't capable, as FED points out, it is because when an untrained pilot tries it, messes it up and then crashes, the manufacturer would be liable.
Helicopters get abused in for more 'legal' ways than this - being flown constantly at high AUM, VNE, in turbulent conditions, all of which are non-reportable (all within the RFM) and all of which degrade the components quicker than the TBO stated by the manufacturer who will assume a wider spectrum of usage.
If you buy a German car in Africa they remove a number of sportier options from the list because we are in a "rough road" country. The warranties they offer just don't last when treated roughly.
Civilian helicopters are no different.
When something unexpected happens the manufacturers are liable and it's next to impossible to trace the history back to a handful of bored high-hour pilots.
If you want to be chuck Aaron get a sponsorship from redbull.