I think that pellets are a great supplement to a parrots diet, seeing as they can last longer than fresh food which you would have to replace every 2-3 hrs depending on temp and also for the night and early morning since fresh food would spoil. An all fresh vegetable or chop diet would be incredibly hard to maintain especially if you work, go to school, or ever need to leave the house aka majority of people. Plus chop while amazing can often lack important nutrients and vitamins key to a healthy parrot, for example such as vitamin D3 and vitamin A which most pet birds are lacking in, quality pellets such as Harrison's will have that added in to make sure that your pet bird receives all the necessary nutrients. If you are concerned about your amazon eating too many pellets you can weigh the daily amount or measure out a set limit that would be appropriate given his age/species/weight/ etc. This is a great guide to a variety of pellets available
Pellets for Parrots .
If you don't mind me asking what is it about this friend of yours that seems more qualified than someone who studied parrots such as an avian vet? and since you place more importance on experience it may be useful to know that many members on AA have been experienced bird owners of 30+ years who have incredibly happy and healthy birds. Just my opinion.
My conure gets a very diverse and well rounded chop every morning and will eat that until either he finishes or until its no longer fresh, after which I will measure out his Harrison's fine daily maintenance Pellets which he will eat as needed or munch on through the night or morning.
I'll tag some more Amazon owners
@jmfleish @Elysian