As I see it, the problem with violating such a rule would be that if/when other high-power appliances are connected to the circuit, there could be a high incidence of nuisance tripping.
That in itself wouldn't be a problem so long as the OCPD and cables are properly sized. The only real safety issue I can see is that regular nuisance trips might lead to some uninformed person deciding to uprate the breaker in order to "solve" the problem. Then it could most definitely be a safety problem.
