It's not like larger fish tend to sit there and chew flakes to bits, they're more likely to simply inhale them ime. That said, I noticed a long time ago that fish tend to grow faster on pellets, it's just a more efficient way to feed a staple food when you compare weight to weight and how many flakes it would take to equal a few decent sized pellets. Also less potential for water soluble nutrients to dissolve away before the fish get them.
In my early days I grew cichlids on flakes. So, sure, it's possible. But that didn't last long after I found pellets were more efficient, especially for most fish with any size to them, and there aren't many products/ingredients you can't get just as easily as a pellet.