Hans, your answer can be found in the article you linked:
Article 240-2.09 relating to the International Regulations for Preventing Collisions at Sea (RIPAM) states that " Pleasure craft are required to comply with the provisions made applicable, depending on the ship's characteristics, by Decree 77-733 of 6 July 1977 publishing the Convention on the International Regulations for Preventing Collisions at Sea, 1972, done at London on 20 October 1972. "
In short, ships, even pleasure craft, must comply with these regulations. Therefore, if the characteristics of the vessel require that an anchor ball be carried by the RIPAM, it must be on board in application of article 240-2.09.
The Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) 1972 apply to both Inland and International waters. I guess one could argue that they never anchor if questioned about the location of their ball but I'm sure that won't go over well with the inspection team
Anyway, sorry to bore all of you...let's get back to the important stuff of getting our boats back in shape for boating season!