This is a great topic for discussion and one that I’m aware of.
The recommendations are based on direct correlations, ie there is a reduced all-cause mortality and morbidity risk if you consume over 5 fruit and veg per day; indeed, this reduces further with increasing amounts.
However, this is based on comparing either eating F and V with not. There is no taking into account of which nutritional factors are important or alternative ways of getting these nutrients. Consuming Huel supplies all the fibre, vitamins and minerals that fruit and veg do, as well as a god bunch of phytonutrients.