Most fish will eat anything, but they're like us in that. A lot of what we feed may not be good for them.
I used to feed whatever flake was cheap. Then I learned about different digestive systems, herbivores, omnivores, etc, and started trying to vary. I started using freeze dried tubifex, brine shrimp and mosquito larvae 40 years ago, and only gradually phased them out for practical reasons - cost mainly with more tanks here. They're good food.
Flake and pellet food have improved, but I still use them as sparingly as I can. In my own life, I largely stopped eating processed foods because of a health issue, and have been pleasantly shocked at the weight loss I've experienced since then. I figure it's the same with my fish - I see less egg binding in tetras with 'bare bones food' (freeze dried, frozen, insects and cultured live foods), better colour, more breeding and overall better lifespans.
The downside is it takes a little more time and space, and costs more. Still, compared to feeding my dog, it's nothing.
Leaving aside the live foods, I now have decapsulated brine shrimp eggs, bug bites (veggie and colour), algae wafers and a few powdered foods for tiny fry. If I could get a deal on tubifex cubes, I would use them. If freeze dried black mosquito larvae were still available, I'd buy it. I wouldn't buy freeze dried brine shrimp (too fractured by the process) or daphnia (not very effective food freeze dried), and bloodworms are an allergy problem for me, and many others.