It's the classic thing about being 'healthy', 'ideal' and 'beautiful' - models are often regarded as such. Fashion is sold as a dream to consumers ("buy this and you too can be an ethereal, beautiful being", "this suit will make you look powerful and wealthy", etc), after all.  I guess mayos believe that if they can call themselves models, they too will have what it takes to be regarded as universally beautiful. What they fail to realise is that they look, at best, like really bad parodies of actual models.