The same rules apply over here as well (although it pertains to a dive leader not just a DM - sorry, me just being pedantic, anyway, i digress!)..due to MAFF (Ministry of agriculture, forest and fisheries) regulations. (look
here for more info)
I think it's more to do with protecting the aquatic life and environment etc, plus from a safety - and probably liability for the resort - perspective (you'd never have guessed i'm doing my rescue ;) ) it confirms that divers who go, do come back and help is available if they need it.
Just my 2psi's worth