Antoine.
If you take a good look at the original; a Hong Kong schooner, you will notice how extreme those rigs are. The AR is extremely low, the fanning goes from bottom to top and 95%+ of the mainsail sits aft of the mast. You will also see how the Hong Kong parrels are struggling, and bend the battens upwards, even if these appear to be made up of bundles of bamboo. The forces in that rig must be huge. My armchair guess is that they wanted to pile on as big sail as they could on a short (read: less expensive) mast. Also note how well all those panels are setting - the HK-parrels surely must do their job well - and the crew were pros.
The situation on the latest Fantail style (as with my Johanna-style) rigs is very different. Here most of the fanning is in the top 3-4 panels. If the sail can be peaked up with the use of a THP and YHP (plus moving the slingpoint a bit aft of the middle), the panels below will stay mostly in place without any need for HK parrels. I still fit them, but there is very little load on them after the THP and YHP have been set up.
Arne